Copredication in homotopy type theory Hamidreza Bahramian1, Narges Nematollahi2, and Amr Sabry3 1 Department of Computer Science, Indiana University, Bloomington, USA habahram@indiana.edu 2 Department of Linguistics, Indiana University, Bloomington, USA nnematol@indiana.edu 3 Department of Computer Science, Indiana University, Bloomington, USA sabry@indiana.edu April 28, 2018 Abstract This paper applies homotopy type theory to formal semantics of natural languages and proposes a new model for the linguistic phenomenon of copredication. Copredication refers to sentences where two predicates which assume different requirements for their arguments are asserted for one single entity, e.g., "the lunch was delicious but took forever". This paper is particularly concerned with copredication sentences with quantification, i.e., cases where the two predicates impose distinct criteria of quantification and individuation, e.g., "Fred picked up and mastered three books." In our solution developed in homotopy type theory and using the rule of existential closure following Heim analysis of indefinites, common nouns are modeled as identifications of their aspects using HoTT identity types, e.g., the common noun book is modeled as identifications of its physical and informational aspects. We show that HoTT provides a different view of tackling the puzzling phenomena of copredication. 1 Introduction In formal linguistics the organization of grammar is viewed as involving a number of (relatively) independent subsystems, including phonology, which deals with the sounds of the language, morphology, which studies the smallest units of meaning in the language, syntax, which focuses on how the units combine to make a grammatical sentence, and semantics, which is the focus of this paper and studies the meaning of a grammatical sentence based on the meaning of its constituents. In theories of formal semantics, the assumption is that the meaning of the sentence is related to the meanings of its parts in a systematic way. This assumption which is usually attributed to the 19th century German logician, Gottlob Frege, is called the Principle of Compositionality, and can be formulated as follows: Principle of Compositionality: The meaning of a compound expression is a function of the meanings of its parts and of the way they are syntactically combined [35]. Considering the Principle of Compositionality, the task of theories of formal semantics is twofold: 1) defining the lexicon by providing the semantic denotations for the constituents, and 2) setting some rules which combine the constituents as defined in the lexicon and return the truth conditions of the sentences. In the framework of formal semantics, the semantic denotation of a linguistic expression is represented by J⋅K which is called the Interpretation Function and which maps linguistic expressions to their semantic denotations. For example, if α is a linguistic expression, JαK is the semantic denotation of α. As a brief review of the systems of formal semantics that have been developed so far, the pioneering work of Montague1[31] as well as all the later works in the Montague tradition use Church's simple type theory [10]. More recent works (e.g., [37, 29]) employ dependent type theories like Martin-Löf's type theory [33] and the Unifying Theory of dependent Types [26]. The copredication phenomenon has been recently the topic of many discussions in the field of formal semantics (e.g., [2, 3, 17, 8, 5, 38]). Copredication sentences are those where two predicates with different requirements on their arguments are asserted for one single entity. For example, sentence (1c) below represents a copredication sentence: (1) a. The lunch was delicious. b. The lunch took forever. c. The lunch was delicious and took forever. Delicious is a predicate which is normally used of food but not events, while took forever is a predicate which normally holds of events and not of food. As Cooper [13] points out, if we were only dealing with sentences like (1a) or (1b), we could present them as instances of polysemy by saying that lunch is ambiguous between a food interpretation and an event interpretation, or in terms of types, we could say that lunch in some cases is of type Food, and in some others of type Event. However, cases like (1c) where one occurrence of the word simultaneously has both interpretations gives rise to the question as what type should we assume for lunch. For the purpose of this paper, we distinguish between three kind of lexical ambiguity: homophony, underspecified2 and metaphor3: homophony refers to cases where two semantically different words happen to have the same phonological form (e.g., bank as office or as land), underspecified refers to the phenomenon that one and the same word is being considered through its different aspects (e.g., book as its physical aspect or as its informational aspect), and metaphor refers to cases where a word is used in place of another word by virtue of some semantic relation between the two (e.g., newspaper as the institution publishing newspapers). What we are considering in this work is the case of underspecified as it seems it is where felicitous copredications are possible. In what follows, first we will look at the treatment of the problem of copredication in Montague's system (Sec. 2), in a modified [20] version of Montague system (Sec 3), and in formal semantics based on modern type theories (Sec 4). After pointing out the shortcomings of each solution, we will then propose a model based on homotopical interpretation of identity types in pure intensional type theory, and show that it can adequately address the complexity of copredication sentences. 1 The Montagovian setting uses a logic for meaning assembly(simply typed lambda calculus) and a logic for semantic representation(higher-order predicate logic)[32]. 2 We borrow this term from [42], where one of the tests to distinguish between underspecified and polysemous (which constitutes homophony and metaphor) is the felicity of relevant copredications. 3 What we call here metaphor includes both metaphor and metonymy as they are defined in [23]: Metonymy is "The part taken for the whole", whereas metaphor is "One word for another". 2 Copredication in Montague semantics In Montague's system there are only two basic types: the type e which represents entities, and the type t which represents truth values. De refers to the set of all entities, and Dt is the set of all truth values, consisting of 0 for false sentences and 1 for true sentences. All linguistic items are taken as functions of these two basic types. Following the established notation, the type of functions from De to Dt is ⟨e, t⟩. Thus, in the case of sentence (1), delicious and took forever are taken as predicates of type ⟨e, t⟩, and the connective and is defined as a function of type ⟨⟨e, t⟩, ⟨⟨e, t⟩, ⟨e, t⟩⟩⟩. For the sake of simplicity and since it has no direct bearing on our discussion, we do not include tense in our analysis, and treat took forever as an atomic predicate rather than the past tense form of take plus the temporal adverb forever. The copula (was), on the other hand, is taken as semantically vacuous, so delicious and was delicious have the same semantic values. Therefore, the lexicon of sentence (1) is defined as follows4: Jwas deliciousK = λx ∈De. x was delicious Jtook foreverK = λx ∈De. x took forever JandK = [λf ∈D⟨e,t⟩.[λg ∈D⟨e,t⟩.[λx ∈De. f(x) = g(x) = 1]]] JlunchK = λx ∈De. x is a lunch JtheK = λf ∈D⟨e,t⟩&(∃!x ∈De [f(x) = 1]). !y [(f(y) = 1)], where ∃!x [φ] abbreviates "there is exactly one x such that φ" and !y [φ] returns "that unique y such that φ". Regarding the rules which combine the constituents of the lexicon, the only rule that we need for sentence (1) is Functional Application which is formulated as follows: (2) Functional Application (FA) [20]: if α is a branching node with β and γ as its daughters, then α is in the domain of J⋅K if both β and γ are, and if JγK is in the domain of JβK. In this case, JαK=JβK(JγK). Applying Functional Application5 to the lexicon defined above, we will have the following denotations for the upper nodes: (a) calculates the semantic value of was delicious and took forever where and takes the two predicates was delicious and took forever as its two arguments and returns a function of type ⟨e, t⟩. (b) calculates the semantic value of the lunch where the takes lunch as its argument and returns the unique lunch the details of which are shared by participants of the conversation. Finally (c) calculates the semantic value of the whole sentence, returning 1 iff the lunch was delicious and took forever. (3) a. λx ∈De. was delicious(x) = took forever(x) = 1 was delicious and took forever 4 In the definition of JtheK, what the condition ∃!x ∈ De [f(x) = 1] wants to express is the partiality of the function. We want to return an object only if there is only one such object otherwise, the function should fail to return. 5 We can apply FA to a node if one of its children is an argument to the other. Based on the definition of FA, it does not matter whether the argument is the left child or the right one. b. ! y [lunch(y)=1] the lunch c. 1 iff was delicious(the lunch) = took forever(the lunch) = 1 the lunch was delicious and took forever The previous example suggests that the Montague semantics can handle the copredication sentence in (1c) without difficulty. However, a more precise analysis reveals that Montague semantics makes too many identifications. More precisely, all individuals are assigned type e, and consequently predicates always take arguments of type e; the lunch for example is assigned type e no matter if it is used in its food or event sense and delicious takes an argument of type e even though we know that delicious does not make sense with the event aspect of lunch. As a consequence, while Montague semantics avoids some possible problems in copredication sentences such as (1c), it is unable to provide the correct semantics in examples including quantification where the two predicates impose distinct criteria of individuation [17]: (4) a. Fred picked up three books. b. Fred mastered three books. c. Fred picked up and mastered three books. The predicate picked up deals with the physical aspect of books, whereas mastered is concerned with the informational aspect of books. We observe that the two predicates impose distinct criteria of individuation on their arguments: on one hand, sentence (4a) is true iff Fred picked up three books that are physically distinct, even if they are for example three copies of the same book, i.e., being informationally the same. On the other hand, sentence (4b) is true iff Fred mastered three books that are informationally distinct even if all three are contained in a trilogy, which is counted as one physical object. Combining the two predications, sentence (4c) is therefore true iff Fred picked up and mastered three books which are both physically and informationally distinct. In order to see if Montague semantics can handle sentences like (4), we first define the lexicon: JFredK = Fred Jpicked upK = λx ∈De.λy ∈De. 1 iff y picked up x JmasteredK = λx ∈De.λy ∈De. 1 iff y mastered x JbookK = λx ∈De. 1 iff x is a book JthreeK = λf ∈D⟨e,t⟩.λg ∈D⟨e,t⟩.∃x1, x2, x3 ∈De such that x, y, z are distinct and [f(xi) = g(xi) = 1 for i= 1,2,3] The syntactic tree for (4b), shown in (6d) exhibits the accepted practice of quantifier raising in the case of quantified objects [20], where the quantified object is raised to a higher node, and leaves behind a trace (ti) of type e. Then, in order to relate the trace with the raised object, we add a branch to the tree which has only a numerical index, co-indexed with the trace, right below the raised object. So in the case of our example, in (6d), first we raise the object three books to a higher node, and call its trace t1. We note that t1 is of type e, and composes with its neighbors just like any other element of type e. Then, in order to relate the raised object to its trace, we add a branch with the numerical index 1, co-indexed with the trace, right below the raised object. Now we calculate the semantic value of the tree step by step. (a) and (b) apply Functional Application and calculate, respectively, the semantic value of mastered t1 and Fred mastered t1. But to calculate (c), we need a new compositional rule, called Predicate Abstraction (PA) shown in (5). This rule essentially says that in calculating the semantic value of a certain point of a tree, if we encounter a branch with a numerical index (like branch 1 in (6d)), which reflects that we have a raising operation, then we need to replace in the semantic value of that point of the tree the trace of the same index (i.e., t1 in (6d)) with the variable x. By so doing, we make the semantic value into a function that can take the raised object as its argument and thereby, replace the trace with the raised object. So in the final step, shown in (d) the raised object three books is composed with the lower node, which is now a function expecting an argument of type e, through Functional Application. (5) Predicate Abstraction (PA) [20]: Let α be a branching node with β and γ as its daughters, where β dominates only a numerical index i. Then for any variable assignment g, JαKg=λx ∈De. JγKg[i→ x]. (6) a. λx ∈De. x mastered t1 mastered t1 b. 1 iff Fred mastered t1 Fred mastered t1 c. λx ∈De. 1 iff Fred mastered x 1 Fred mastered t1 d. 1 iff ∃x1, x2, x3 ∈De [book(xi)=1 and mastered (Fred,xi)=1 for i=1,2,3] three books 1 Fred mastered t1 As (6d) shows, in Montague semantics (4b) is true iff there exist three books x1, x2, x3 which Fred mastered. There is no explicit restriction to establish how the three books are individuated, i.e., physically, informationally or both. Consequently, it is unclear how the system responds to scenarios where Fred mastered a trilogy contained in one single volume. The same unclear situation arises in response to sentence (4a), which requires three physically distinct books, and the copredicated sentence in sentence (4c) which needs three physically and informationally distinct books. 3 Copredication in modified Montague semantics In the semantic framework of Heim and Kratzer [20], which is based on Montague semantics, the requirements imposed by predicates on their arguments is modeled by taking the predicates as partial functions. So, delicious in (1) is no longer a total function from the set of individuals (of type e) to truth-values (of type t); rather, it is a partial function defined only for a subset of individuals, i.e. only for things with a food property so that delicious can be applied to them. Similarly, took forever is a partial function defined only for the subset of individuals with an event property. One of the main motivations for taking the predicates as partial functions in this framework is to be able to rule out sentences like the chair laughed, because the predicate laugh in this framework is undefined for inanimate entities. In the case of our examples, for the compositions in (1a) and (1b) to go through, the lunch in (1a) must be an entity belonging to the domain of delicious and in (1b) to the domain of took forever. Heim and Kratzer do not go into details about the possible operators between partial functions, but we can deduce that for the composition of (1c) to proceed, the lunch needs to be in the intersection of the two domains, so it needs to be both an entity of food property and that of event property, which is indeed the case. In (4b) mastered is taken as a partial function defined for entities with an informational property and undefined otherwise. Therefore, (4b) is true iff there exist 1) three distinct entities (i.e. three distinct elements of type e) such that 2) each one is a book (i.e. the predicate (λx.x is book) returns true for each one of the entities) and 3) each one is informational (so that for each one the predicate mastered can be defined). These three conditions confirm that there are three distinct books, but do not guarantee that the three books are informationally distinct. The problem here, just like in Montague semantics, is that distinction is attributed to elements of type e, the only type for individuals that we have in simple type theory, and it is not clear how to define the criteria of distinction for elements of type e. While "three distinct informational entities" or "three distinct physical entities" can be clearly defined, when it comes to nouns with more than one aspect, like the common noun "book", the term "three distinct books" is ambiguous. What does it mean for three books to be different from each other? Does it mean that they are physically distinct or informationally distinct? This shows that taking predicates as partial functions cannot help with the problem of criteria for quantification; Heim and Kratzer's semantics has the same problem as Montague semantics in that it cannot produce the correct truth condition for a sentence which involves quantification, in simple and copredicated sentences. To sum up our discussion so far, we saw that the main problem is to define the criteria of quantification for nouns that have more than one aspect. So in the case of the common noun "book" characterized by two aspects, physical and informational, we can either say that three books are distinct when they are distinct in just one of the aspects or when they are distinct in both aspects. In the former case, if we say that they are distinct when they are physically different, then the system wrongly returns true for "Fred mastered three books" even if the books are informationally similar. On the other hand, if we say that books are distinct when they are different in both physical and informational aspects, the system wrongly returns false for "Fred mastered three books" if they are contained in one single volume of a trilogy. We observe that what is needed is to develop a dynamic criterion of quantification which is defined based on the predicate. 4 Copredication in extended type theories In theories of formal semantics which employ multiple-sorted type theories, sortal requirements that are imposed by predicates on their arguments are encoded in the type system [37, 28]. Consequently, these systems are characterized by a richer inventory of types than in Montague semantics, since for example, instead of type e, we have various types Physical, Animate, Inanimate, etc., which represent respectively physical, animate and inanimate entities. Furthermore, common nouns are also defined as types, and not functions of type ⟨e, t⟩ as in Montague semantics6. So for example, book denotes the type Book. Extending the inventory of types, however, brings about some type mismatch problems which require additional tools/extensions to type theory to resolve. As a simple example, in a sentence like (7), John could be of type Man, but shout as a predicate would take an argument of type Human, and thus the semantic system encounters a type mismatch and wrongly predicts that the sentence is uninterpretable. (7) John shouts. In order to avoid such problems, Luo [27] uses the notion of coercive subtyping, symbolized by <c as follows: for two types A and B, A <c B indicates that there is a unique implicit coercion from type A to type B in the sense that an object of type A can be used in any context requiring an object of type B. In sentence (7), Man is a subtype of type Human, and therefore, the coercive subtyping rule tells us that John of type Man can be composed with shout which requires an object of type Human. A related extension to type theory is the notion of dot types, which is introduced by Pustejovsky [36] in his treatment of copredication sentences, and is defined as follows: dot types are compositions of two types which nevertheless allow the two individual types to be recovered. Luo [29] then includes his notion of coercive subtyping into dot types and asserts the following statement about dot types: A.B is only well-formed if A and B do not share common components, and both projections, one from A.B to A and the other from A.B to B, are coercions in the coercive subtyping framework. Sentences in (1), for example, involve a type defined as Food.Event, for which the following statements hold: (8) a. Food.Event <c Food b. Food.Event <c Event According to the definition of coercive subtyping, if we include the type Lunch, we will have: 6 As it is discussed in detail in [6] and [9], using types to model nouns prevents their predication. For example, the sentence "Iliad is a book", is then a type assertion, Iliad : Book, not a proposition. In [9], a theory for predicational forms of judgmental interpretations is introduced and it is argued to be able to deal with the issue appropriately. We would however suggest a simpler solution: The semantic denotation of the sentence "Iliad is a book" can be considered to be the following type: there exists an element b : Book such that (b = i), where i is the semantic denotation of Iliad. Similarly the semantic denotation of the sentence "The horse is not a book" would be the following: there is no element b: Book such that (b = h), where h is the semantic denotation for the horse. a. Lunch <c Food.Event <c Food b. Lunch <c Food.Event <c Event Then, by means of contravariance for function types, we derive the following relationships from rules in (8): (9) a. (Food → Prop) <c (Food.Event → Prop) <c (Lunch → Prop) b. (Event → Prop) <c (Food.Event → Prop) <c (Lunch → Prop) Considering the subtyping relationships shown in (9), we can now analyze sentences (1a-1c): in (1a), was delicious, defined as Jwas deliciousK = λA∶F ood.A was delicious, needs an object of type Food, but the lunch is an object of type Lunch. The subtyping relationship in (8a), however, says that an object of type Lunch can be used in any context which requires an object of type Food, and thus the composition can proceed. The same thing applies to (1b). As for the copredication sentence in (1c), delicious and take forever are identified as instances of "conjoinable types" [7], i.e., they can be coerced to the common type Food.Event→ Prop. Therefore, as shown in (10), was delicious and took forever is a predicate which needs an object of type Food.Event, which is satisfied in (1c) because the lunch is of type Lunch, which is a subtype of Food.Event. (10) a. λx∶Food.Event. was delicious(x) & took forever(x) λx∶Food.was delicious(x) and λx∶Event. took forever(x) So far it seems that the notion of dot types along with the theory of coercive subtyping has been able to provide a solution for the case of copredication. Now, we will examine this approach for copredication sentences such as (4c) which includes quantification with distinct criteria of individuation. In (4c) picked up takes an argument of type Physical, whereas mastered needs an argument of type Informational. Assuming quantifier raising just as we did in the previous section, the analysis for (4c) proceeds as follows: (11) a. λB∶Book→Prop.∃x, y, z∶Book[B(x) ∧B(y) ∧B(z)] λA∶T ype.λB∶A→Prop.∃x, y, z∶A [B(x) ∧B(y) ∧B(z)] three Book∶Type books b. λz∶Phys.Info.λx∶Human . (picked up(x,z) & mastered(x,z)) λz∶P hys. λx∶Human . picked up(x,z) picked up and λz∶Info. λx∶Human. mastered(x,z) mastered c. λz∶Phys.Info. (picked up(Fred,z) & mastered(Fred,z)) Fred picked up and mastered t1 As can be seen in (11a), three books needs an argument of type Book→ Prop as its input, and Fred picked up and mastered t1 in (11c) provides an object of type Physical.Informational→ Prop. Considering the covariance relationships similar to what we have in (9), we know that the latter is a subtype of the former, and thus the composition proceeds as in (12). (12) a. ∃x, y, z∶Book [picked up(Fred,x) and mastered(Fred,x) picked up(Fred,y) and mastered (Fred,y) picked up(Fred,z) and mastered (Fred,z)] λB∶Book→Prop. ∃x, y, z∶Book [B(x) ∧B(y) ∧B(z)] three books λz∶Phys.Info. (picked up(Fred,z) and mastered(Fred,z)) Fred picked up and mastered t1 In the analysis shown in (12), quantification is still carried out over objects of type Book, because it returns the truth-condition of (4c) as follows: the sentence is true iff there are three books x, y, z which Fred picked up and mastered. Including the notion of coercive subtyping, however, we have the following coercive relations: (13) a. Book <c1 Physical b. Book <c2 Informational which enable us to replace picked up (Fred,x) in the final analysis of (12 ) with picked up (Fred, c1(x)) and similarly mastered (Fred,x) with mastered (Fred, c2(x)). So the truth-condition shown in (12) can be reformulated as follows: (14) ∃x, y, z ∶ Book [picked up(Fred, c1(x)) and mastered(Fred, c2(x)) picked up(Fred, c1(y)) and mastered(Fred, c2(y)) picked up(Fred, c1(z)) and mastered(Fred, c2(z))] As we already mentioned in previous sections, intuitively we judge that (4c) is true iff the three books picked up and mastered by Fred are both physically and informationally distinct. The truth-condition formulated in (14), however, does not agree with this intuition unless we add an additional axiom to the system, as Chatzikyriakidis et al. [8] also point out in a footnote (fn.9); in coercive subtyping in general, when X <c Y, the proposition x ≠X y does not entail x ≠Y y unless c is injective. Applying this general rule to (14) then, having three distinct objects of type Book, i.e., x, y, z does not entail that the corresponding coerced objects in Physical, i.e., c1(x), c1(y) and c1(z) are also distinct. Chatzikyriakidis et al. therefore, state that they axiomatically assume so for the atomic types like Book and Physical. While this assumption drives the desired meaning for (14), it creates some other problems: If c2 is injective, then there cannot be two distinct books whose content is the same. Let x, y be two copies of the same book. So since c2(x) = c2(y) and c2 is injective, we will have x = y. Since c1 is also injective, we will have c1(x) = c1(y) and therefore the books are physically the same which is a contradiction. A similar approach can be found in [5] where a subtype relation is represented as an injection sending an element of a type to itself which is then regarded as an element of its supertype. For polysemous common noun it is assumed that a number of aspect functions exist such that each one send an object of a common noun to one of its aspects: aspI : Book → Info aspP : Book → PhyObj Aspect functions are different from injections of subtype relations. When encountering a type mismatch, the type of the functions is being shift, instead of the type of nouns (which are arguments to the functions). Aspects are used to shift the type functions when it is needed: pickup is the term λyλx. pickup(x, y) of type Physical → Animate → Prop which by by the CCG-style functional composition with the aspect function aspP shifts to the term λyλx. pickup(x, aspP (y)) of type Book → Animate → Prop. As a result, the denotation of the sentence Fred picked up and mastered a book will be the term ∃y7 (book(y) pickup(Fred,aspP (y)) master(Fred,aspI(y)) ). [5] does not mention how it might handle the individuation problem. If the denotation for three is similar to that of a, then we will probably end up having something like (15): (15) ∃x, y, z [book(x) ∧ pickup(Fred, aspP (x)) ∧ mastered (Fred, aspI(x)) book(y) ∧ pickup(Fred, aspP (y)) ∧ mastered (Fred, aspI(y)) book(z) ∧ pickup(Fred, aspP (z)) ∧ mastered (Fred, aspI(z))] The result however has the same inadequacy as (14). Here we assert that there are three distinct objects of type book such that Fred picked up their physical aspects and mastered their content. But whether their physical aspects are distinct or their content are distinct is remained unspecified resulting problems we alluded to before. 5 Copredication in the Montagovian generative lexicon [38] uses many-sorted higher order predicate calculus for semantic representation where the sorts are the base types. Meaning assembly is done using second order λ-calculus (Girard system F) as opposed to Luo's use of type theory with coercive subtyping. A a word in the lexicon is associated with a a finite set of λ-terms, one of them called the principal ?-term, the other ones are called optional. Words and constituents compose using the functional application rule. Semantic incompatibility is modeled by type mismatch as before. To allow an a priori type mismatch where it is legitimate, the optional λ-terms are used.The optional 7 [5] do not specify the type of the existential variable y here. Our guess is that the type of this variable is the type Entity which is a supertype of Book. terms, change the type of the function or the argument under composition to resolve the type mismatch. To allow or block felicitous and infelicitous copredications, optional λ-terms are tagged as rigid or flexible. Flexible terms can be used without any restriction. Rigid terms cannot be used in copredication sentences. Consider the following example: (16) a. Liverpool is spread out. b. Liverpool voted. c. Liverpool won. d. Liverpool is spread and voted last Sunday. e. # Liverpool voted and won last Sunday. Assuming the base types are defined as follows: F ∶ football team T ∶ town P ∶ people Pl ∶ place Assume the principal term for Liverpool is a term of type T and its optional λ-terms defined as: t1 ∶ T → F rigid t2 ∶ T → P flexible t3 ∶ T → Pl flexible Now t3 is used to resolve the type mismatch in (16a), t2 for (16b), etc. The flexibility of both t2 and t3 give an account for the felicity of (16d) and the rigidity of t1 handles the infelicitous copredication in (16e). [38] does not elaborate on the individuation problem in copredication sentences, so it is unclear to us if the setting, outlined in [38], has an account for handling individuation or not. 6 A mereological approach to copredication In [15] Gotham distinguishes between three approaches to copredication: 1) merelogical accounts (e.g., [12]). 2) Type Composition Logic (e.g., [3]). 3)Pragmatic accounts involving lexical ambiguity (e.g., [34]). According to him Existing attempts to devise theories that predict ontologically respectable paraphrases as the natural language interpretations of copredication sentences all face problems of greater or lesser severity when it comes to extending those theories to cases where the copredication sentences involve numeric quantification. The general issue is that copredication presents us with divergent criteria for identifying objects falling under the denotation of the noun, and hence potentially divergent criteria for individuating and counting those objects. Native speaker judgements about copredication sentences involving numeric quantification do not perfectly reflect the counting and individuation criteria that the existing accounts predict. Gotham proposes a compositional system for criteria of individuation that improves predictions regarding the truth conditions of quantified copredication sentences ([16]). In this framework the denotation of a transitive verb, tverb, is defined as (17) JtverbK = λxλy < tverb(x,y),a mechanism specifying the individuation criteria of x and y >. The denotation of a common noun, cnoun, is defined as (18) JcnounK = λx < cnoun(x),a mechanism specifying the individuation criteria of x >. The variables in (17) and (18) are of type e, but this type is understood as what (??) proposes. The domain of type e contains both singular objects and proper pluralities. A single object can be a composite object made up of parts. To indicate that a single object is a composite objects, it is written as the sum of its parts. For example a + b indicates a single object whose parts are a and b. a⊕ b indicates the plurality made up of a and b. So, for example, a + b⊕ c + d indicates a plurality made up of two single objects each of which being itself a composite object. The mechanism that specifies the relevant individuation criteria in (17) and (18) is defined as a partial order between relations: Let PHYS be a binary relation such that (a, b) ∈ PHY S if and only if a and b are physically equivalent. The binary relation INFO is defined similarly. Then the lexical entry for the verb pick up is defined as (19) Jpick upK = λxλy < pick up(x,y), λf.f(x) ⊑ PHY S ∧ f(y) ⊑ ANI >. where ANI is the relation of animate equivalence and the partial order ⊑ is defined by the following recursive definition: (20) a. If X ∶ t and Y ∶ t, then X ⊑ Y def= X → Y . b. If X ∶ a→ b and Y ∶ a→ b, then X ⊑ Y def= ∀v(X(v) ⊑ Y (v)). [16] argues that the above implementation for the individuation criteria mechanism allows different individuation criteria to combine monotonically. For example, if f(x) ⊑ PHY S and f(x) ⊑ INFO, then we will have f(x) ⊑ (PHY S ⊓ INFO), where the meet operation, ⊓, means that (a, b) ∈ (PHY S ⊓ INFO) if and only if a and b are physically equivalent and a and b are informationally equivalent. The criteria for individuation for the predicate heavy, is based on the physical aspect of the thing it describes. The criteria of individuation for books is based on both aspects of books; that is, two books are equivalent if they are physically and informationally equivalent. Now the individuation criteria for heavy books is calculated as to be based on the physical aspect, as desired. Now the numerical determiners are defined such that they have access to the individuation information and can exploit that information. By associating lexical entries with a criteria of individuation (or additional information relevant to individuation) and providing a mechanism so that individuation criteria can compose with each other, Gotham provides a framework that delivers all the criteria of individuation that are necessary for copredication and non-copredication sentences. A result which is however achieved, as [25] 8 mentions, at the expense of an enormous amount of ingenuity and complication. 8 The paper [25] argues that the noun "book" does not apply to a kind of object that is individuated both informationally and physically. The sentence that they use to present their argument is the sentence "Three informative books are heavy". Now their argument is not applicable to the sentence "Fred picked up and mastered three books". In fact, almost all the examples that they use are those whose verb is either "is" or "are".We do not agree with how Gotham analyses the sentence "Three informative books are heavy". We think the verb "are" here is not vacuous. It has a semantic function just like any other verb has. According to our theory, "three informative books" can be any of the followings: 1)Three physically distinct, but informationally the same, informative books 2) Three informationally distinct, but physically the same, informative books and 3)Three informative books that are both physically and informationally distinct. Now the predicate "are heavy" restricts the possible meanings to the readings 1 and 3. 7 Copredication in homotopy type theory The relation between the concept of book and the concepts of physical things and informational things is puzzling. One option is to say that this relation is an "is a" relation: a book is a physical thing and a book is an informational thing. In section 4 an implementation of this option was presented and its shortcomings were discussed. Another option is to say that this relation is a "has a" relation. That is, to maintain that the relation between book and its aspects is the relation between a whole and its parts. According to this option, there are four possibilities for the criteria of individuation of books: 1) Books are distinct if they are distinct physically. 2) Books are distinct if they are distinct content-wise. 3) Books are distinct if at least one of their parts are distinct. 4) Books are distinct just in case they are distinct in all their parts. However in the following scenario none of these possibilities work. Consider the following sentence: (21) Fred has five books on the shelf in his study room. The following four cases can be considered: 1. If distinct books are those that are physically distinct (that is, if the criteria of individuation of books is based on their physical aspect) then (21) means that there are five physically distinct books on the shelf. Now assume the situation where we have the following books on the shelf: two copies of Euclid's Elements, Divine Comedy, Iliad and Odyssey. Note that this list of books is compatible with (21) and the criteria of individuation under consideration. Assume that Fred read and mastered all the books on the shelf. Now consider the following sentence: (22) Fred mastered five books. So this case would judge (22) true because there are five books on the shelf. But intuitively (22) is true if and only if there are five informationally distinct books on the shelf. This indicates that the assumption that books are individualized physically is a wrong analysis. 2. For the case where the criteria of individuation of books is based on their informational aspect consider the following scenario: Euclid's Elements, Divine Comedy and The Goldsworthy Trilogy9 (informationally three books but physically only one). The trilogy counts as three books because in this case the criteria of individuation is based on informational aspect of books. Now consider the following sentence: (23) Fred picked up five books. So this case would judge (23) true which intuitively is not the case. 3. Suppose distinct books are those that are either informationally distinct or physically distinct. This case also would judge (23) true for the scenario of the previous case. 4. Suppose distinct books are those that are both informationally distinct and physically distinct (in other words, books are distinct whenever all of their parts are distinct). Now consider the situation where we have the following books on the shelf: Euclid's Elements, Divine Comedy, Iliad and two copies of Odyssey. This case would judge (23) false because according to analysis under consideration in this case, there are not five books on the shelf. 9 a collection of three books in one book In this section, we first give an informal and intuitive account of our proposal. Then there comes a brief introduction to homotopy type theory in which we implement the proposal . The introduction to homotopy type theory is focussed on the aspects of the theory that we are directly using in our implementation, namely the observation that identity type equips each type with the structure of a (weak) ω-groupoid, as studied in higher category theory. While this fact about the identity types is compatible with pure intensional type theory, we use homotopy type theory because the intuition behind our model comes from the homotopical interpretation of identity types, without which it is hard to express or justify the intuition.After the introductory section, we introduce our model and discuss how it deals with the copredication phenomenon. 7.1 A brief informal account of our proposal Quantified multidimensional count nouns, semantically speaking, contain all possible semantic possibilities. When a quantified count noun passes as an argument to a predicate, its semantic value becomes crystalized by shrinking to a subset10 of its possibilities (potentialities). It stays crystalized in the remaining context unless it is passed as an argument to another predicate where it will undergo further crystallization (that is, it shrinks to a yet (possibly) smaller subset of its possibilities). When I hear "three books", what comes into my mind is a range of possibilities: It can be three informationally and physically distinct books, two copy of the same book and a third informationally distinct book, a trilogy, . . . . Then if I hear ". . . picked up three books", the range of the possibilities shrink to those in which there are three physically distinct books. Moreover if I hear ". . . picked up and mastered three books", the collection of possibilities shrink more to those in which there are three physically and informationally distinct books. Similarly if I hear "three easy to understand books" or "three heavy books" the collection of possibilities shrink. But if I hear ". . . bought three books", the set of possibilities remains the same. 7.2 Identity type in homotopy type theory In intensional Martin-Lof type theory, if a and b are objects of type A then the identity type Id(a, b) (or equivalently a = b) is a proposition, namely, the proposition that a and b are identical. [30]. Whether any two elements of an identity type are necessarily equal is a property called UIP (Uniqueness of Identity Proofs). [14] and [1] showed that UIP is derivable in a type theory augmented with pattern matching but [21] proved that UIP is not derivable in pure type theory11. They refute the principle of UIP by providing a counter model interpreting types as groupoids12 where an element of a type is an object of a groupoid and the proof of an equality between two elements is a morphism in the groupoid. Groupoid model shows that we can have multiple different proofs of the same identity. Wether the proofs of equality between proofs can also be multiple is a question which groupoid model even fails to express because in the groupoid structure the notion of morphisms between morphisms is absent. Homotopy type theory ([4] ; [41]) is based on this observation that not only we can have the proof relevant notion of equality between elements but also the 10Depending on the predicate this subset can be a proper subset or it can be equal to the original set of possibilities. 11 Independently, [24] observed that type theory can be considered as an internal language of the category of groupoids. 12A groupoid is a category in which every morphism is an isomorphism. proof relevant notion of equality between proofs of equality and we can continue this proof relevancy of equalities up to infinity 13. A type with exactly one element (up to equality14) is called contractible. We say that a type is a proposition if it has at most one inhabitant15. A type whose equalities are propositions is called a set. It is known that any type with a decidable equality is a set [18]. We say a type is a groupoid if all its equalities are sets. To continue with this hierarchy we say contractible types are of dimension (also called truncation level) 16 -2, propositions are of dimension -1, sets are of dimension 0 and groupoids are of dimension 1. A type has dimension n + 1 if its equalities are of dimension n. That is, a type A has dimension n + 1 if for all x, y in A, the type x = y has dimension n. We say a type A is a n-type if A has dimension n. It is known that we can construct types which are not n-type for any natural number n [22]. 7.3 The model We call a type that is not n-type for any n, an ideal type. We postulate the existence of a universe, U317 that is itself ideal and all of its elements are also ideal and that the following holds: for any equality type (of any order) in U3, the equality is either empty or ideal. The semantic denotation of a count noun is an identity type in U3. The semantic denotation of an object (instance) of a count noun is a nontrivial18 element of its corresponding type. For a count noun and each of its aspects there are types in U3 which we call their prototypes. The semantic denotation of a count noun, then, is the equality between the prototype of the count noun and the prototypes of its aspects. For example, consider the common noun book. If we envisage that it has two aspects, namely physical and informational, then the semantic denotation of the common noun book, JBookK, is defined as (BookPrototype = PhysicalPrototype) = (BookPrototype = InformationalPrototype) where the types BookPrototype, PhysicalPrototype and InformationalPrototype are in U3. The semantic denotation of a book object is defined to be a non trivial element of JBookK. So for example, JIliadK is a non trivial element of JBookK. Note that this definition has an interesting consequence: The existence of a particular book object, for example the book Iliad, entails that JBookK is ideal19. One may argue that this definition of the common noun book is strange or unreasonable because the type of book cannot be equated to the type of physical for the simple reason that books and physical things are not the same. To reply we refer to a popular example in topology: a coffee mug and a donut are the same as far as their topology is concerned. That is, there exists a homeomorphism between the surfaces of 13Such a structure is called a ω-groupoid which in homotopy theory has a model called Kan complex. The model, however, is using the axiom of choice. A constructive alternative model based on cubical sets was proposed in [11] 14That is, a type A is contractible if it has an element a such that for all x in A we have x = a. 15An element of a type has many names: point, element, proof, token, witness or inhabitant. 16To be compatible with equivalent notions in homotopy theory we start counting with -2. 17We choose the index three because number three is associated with the meaning of multiplicity and it is this universe that contains and provides semantic meanings for lexical items. 18This consideration plays an important role in the consistency of our model. We elaborate on this later in this section. 19That is, the existence of the book Iliad affirms the existence of other books which are different from Iliad. Or if we consider geometry as a whole to be a type, then the existence of euclidean geometry affirms the existence of non-euclidean ones. a donut and a coffee mug (with one handle).In other words, two spaces are homeomorphic if one can be deformed into the other by a continuous deformation without using cutting or glueing. If two spaces are homeomorphic, their topological properties will be identical, and therefore they are considered topologically the same. Now we cannot eat coffee mug nor we can drink tea using a donut instead of a mug. Likewise the type of BookPrototype can be continuously deformed into the type of PhysicalPrototype. We interpret "continuously", to mean without stopping being essentially what it was. On the on hand, when a book considered as its physical aspect, this consideration is total, in the sense that we treat the word as if it is a different word with no other aspect or sense. On the other hand, we do not exclude the fact that the physical thing under consideration is a book and indeed at any moment it can be turned into a book again20. The continuity of the deformation can be interpreted to reflect the latter consideration. The semantic denotation of the physicality, JPhysicalK, is defined as (PhysicalPrototype = PhysicalPrototype) The semantic denotation of a physical object is a non trivial element of JPhysicalK. The non triviality assumption is mathematically crucial as we demonstrate later in this section. But one may ask what is the semantic significance of this assumption. We interpret the non triviality requirement as the following: a physical object is a particular deformation of the type PhysicalPrototype into itself. Now a physical object is temporary, that is, it has a start and an end. Its start coincides with the start of the deformation and its end with the end of deformation. In a trivial deformation the start and the end is the same and therefore a physical object corresponding to this deformation has no temporal existence which is contradictory to the nature of physical things. Similar to the denotation of the physicality, we define the semantic of the informational, JInformationalK, as (InformationalPrototype = InformationalPrototype) Considering the definition of JBookK, one may object that as soon as you have an object b of type Book, you will have its inverse b−1. Now what is the semantic interpretation of b−1? We reply that b and b−1 refer to the same book but the accentuation is different. Consider the following sentences: (24) a. Iliad is heavy21 but easy to understand. b. Iliad is easy to understand but heavy. If b is the meaning of Iliad in the first sentence then b−1 would be its meaning in the second sentence. What happens in mind when constructing b, is first a deformation of BookPrototype to PhysicalPrototype and then adding its informational component. Whereas for b−1 it is the morphing of BookPrototype into InformationalPrototype that is happening first. Now we need to show that if we have a book object, we will have a physical object and an informational object such that the physical object can turn into a book object at any moment it is required to do so. Likewise for the informational object. Furthermore we need to 20For example in the sentence "I picked up Iliad and read it", the book Iliad is a physical thing under the predicate "pick up", but it will turn again into a book to become an informational object when it is under the predicate "read". 21Here heavy is intended to mean physically heavy and not metaphorically heavy which would be contradictory to the latter part of the sentence. show that the proposed definition of JBookK affords the fluidity that our hypothesis requires. That is when we say "three books", the semantic denotation should afford all the possible meanings of this utterance22. Consider there is a book object with its semantic denotation denoted by b. By definition b is a nontrivial element of JBookK23. The non-triviality of b entails that none of the types BookPrototype = PhysicalPrototype and BookPrototype = InformationalPrototype is empty. Now an equality in U3 is either empty or ideal, therefore both equality types are ideal. The element b induces an equivalence function, namely f , from BookPrototype = PhysicalPrototype to BookPrototype = InformationalPrototype ([40] Lemma 2.10.1). For the element b we postulates the existence of two elements bp : (BookPrototype = PhysicalPrototype) and bi : (BookPrototype = InformationalPrototype). We define the physical object corresponding to the book object b, calling it b qua physical, as the following: (25) b qua physical = b−1p ○ f(bp) ○ b−1i ○ f−1(bi). So b qua physical is a concatenation of four paths:24 The element bp is a path form BookPrototype to PhysicalPrototype so its inverse is a path from PhysicalPrototype to BookPrototype. The element f(bp) is a path from BookPrototype to InformationalPrototype. The element b−1i is a path from InformationalPrototype to BookPrototype and finally the element f−1(bi) is a path from BookPrototype to PhysicalPrototype. So by concatenating these four paths we construct a path from PhysicalPrototype to itself and therefore we construct b qua physical which is an element of JphysicalK. We believe this definition is determined enough to tie b qua physical to b meaningfully and fluid enough to give freedom to b qua physical to be equal to some other c qua physical for a book object c. Similarly we define the informational object corresponding to the book object b, calling it b qua informational, as the following: (26) b qua Informational = b−1i ○ f−1(bi) ○ b−1p ○ f(bp). We define a sentence to be interpretable if and only if it has a type. The semantic denotation of an interpretable sentence is defined to be its type. Note that according to this definition the semantic value of a sentence is a proof relevant concept. That is, we believe natural language sentences, semantically speaking, are not mere propositions which are either true of false. Rather the meaning of a sentence is a witness, a proof or an evidence (all terms refer to the same thing), or a collection of evidence that the sentence is true. A sentence is meaningless if there is no evidence, no intuition, no proof or nothing that asserts its truth. The things that asserts the truth of a sentence are its denotational meaning. Whether it is one evidence or several ones, proving the truth of the sentence, is the same as far as the truth of the sentence is concerned. Nevertheless as far as the meaning of the sentence is concerned, all those evidence count toward the meaning of the sentence. If I say "Fred is 30 years old", the meaning of this sentence is all the evidence that assert the truth of Fred being of this age. I may have only one of those evidence, which is enough for me to believe that the sentence is true but the meaning of the sentence is all the evidence attesting to its truth. Consider the following sentences: (27) a. Fred picked up Iliad. 22This utterance may mean three physically distinct books or a trilogy or three copies of the same book etc. 23This very fact asserts that JBookK is ideal. 24 Inspired by the homotopical interpretation of types, elements of an equality type are sometimes called paths. So here by concatenating four paths we are constructing an element of JPhysicalK. b. Fred mastered Iliad. c. Fred picked up and mastered Iliad. We define the denotation of the predicate25 in (27a) as Jpick upK = λx ∶ JHumanK λy ∶ JPhysicalK .type of all the evidence26 that x picked up y. We use the notation PICKUP(x, y) to mean the type of all the evidence that x picked up y. We insist on repeating the redundant phrase "all of the evidence" to accentuate the fact that the type under consideration is not a proposal, nor the sentence describing the type is a truth condition. Similarly we use the notation MASTER(x, y) to mean the type of all the evidence that x mastered y. Now assuming JFredK = h ∶ JHumanK and JIliadK = b ∶ JBookK, the semantic value of (27a) is computed as J(27a)K = Jpick upK (h)(b qua physical) = PICKUP(h, b qua physical) Likewise the denotation of the predicate in (27b) is defined as JmasterK = x ∶ JHumanK λy ∶ JInformationalK .MASTER(x, y). So the semantic value of (27b) is computed as J(27b)K = JmasterK (h)(b qua informational) = MASTER(h, b qua informational) As for (27c), we first define the semantic denotation of and as JandK = λAB.ΣAB. Where A and B are types. Note that ΣXY is true if and only if there exists an element x in X for which Y (x) is inhabited. If Y is not dependent on type X, then Y (x) simply means Y . So in a case where Y is not dependent on X, the type ΣXY is inhabited only if both types X,Y are inhabited. The semantic value of (27c) is computed as J(27c)K = Σ(Jpick upK (h)(b qua physical)) (JmasterK (h)(b qua informational)) = Σ PICKUP(h, b qua physical) MASTER(h, b qua informational) Now consider the following sentences: (28) a. Fred picked up three books. b. Fred mastered three books. c. Fred picked up and mastered three books. The semantic value of (28a) is computed as J(28a)K = The type of all the evidence that there exist x, y, z in JBookK such that (the type of all of the evidence that x qua physical and y qua physical and z qua physical are distinct and Σ( PICKUP(h, x qua physical)) (Σ( PICKUP (h, y qua physical)) ( PICKUP (h, z qua physical))))27 Likewise for (28b) we have the following 25We disregard the tense of the verb as it is orthogonal to our analysis. 27When we say ". . . such that (the type of all of the evidence that . . . )", we mean to express the condition that ". . . such that (the type (of all of the evidence that . . . ) is not empty.)". J(28b)K = The type of all the evidence that there exist x, y, z in JBookK such that (the type of all the evidence that x qua informational and y qua informational and z qua informational are distinct and Σ( MASTER(h, x qua informational)) (Σ( MASTER (h, y qua informational)) ( MASTER (h, z qua informational)))) And finally the semantic value of (28c) is computed as J(28c)K = The type of all the evidence that there exist x, y, z in JBookK such that Σ (the type of all of the evidence that x qua physical and y qua physical and z qua physical are distinct and Σ( PICKUP(h, x qua physical)) (Σ( PICKUP (h, y qua physical)) ( PICKUP (h, z qua physical)))) (the type of all the evidence that x qua informational and y qua informational and z qua informational are distinct and Σ( MASTER(h, x qua informational)) (Σ( MASTER (h, y qua informational)) ( MASTER (h, z qua informational)))) 7.4 Computation details In her analysis of indefinites (e.g., a book), [19] takes indefinites as variables and assumes a covert existential quantifier which scopes over the entire sentence and unselectively binds the indefinites in an un-embedded sentence (through the rule of Existential Closure). For example, for the sentence A cat arrived , she assumes the structure shown in (29) as the logical form: first a cat is moved out of its phrase through the rule of NP Prefixing, leaving behind e1. Then ∃1 adjoins to the top node, and binds the indefinite a cat: (29) T ∃1 T S NP1 a cat S e1 arrived We extend this analysis to numbered NPs (e.g., three books) in the following way: in the syntactic tree of the sentence Fred picked up three books, for example, we assume that three books is moved out of its phrase, adjoining to the S node as threed books (d for definite). But in addition to threed books, we assume that there is also threei books (i for indefinite) adjoined to the top node with a similar function as that of the covert existential quantifier in [19]'s analysis28. The semantic denotation of threei is therefore defined as JthreeiK = λA∶U3λD. The type of all the evidence that there exist x, y, z in A such that D, where D is a type containing x, y and z as free variables of type A. the semantic denotation of threed is defined as below: 28As to why there are two "threes" here, apart from the assumption that there is a covert existential quantifier, we can observe the following: when I say "I read three books" what the sentence says in a more detailed way is that "There are three books such that I read the three books". Therefore there are in fact two "three books" in the sentence, one indefinite and the other definite. JthreedK = λA∶U3λB∶C→U3 . The type of all the evidence that that x qua C and y qua C and z qua C are distinct and JandK (B(x qua C))(JandK (B(y qua C))(B(z qua C)), where x, y and z are free variables of type A. 1. Computation of J(28a)K The semantic value of Fred picked up t1 is computed as follows: JFred picked up t1K = λx ∶ JPhysicalK . PICKUP(h, x). Then, we calculate the denotation of threed books. Jthreed booksK = λB∶C→U3 . The type of all the evidence that x qua C and y qua C and z qua C are distinct and JandK (B(x))(JandK (B(y))(B(z)), where x, y and z are free variables of type JbookK. Passing the denotation of Fred picked up t1 to the denotation of threed books, we get the following: J[threed books [Fred [picked up t1]]]K = The type of all the evidence that x qua physical and y qua physical and z qua physical are distinct and JandK (PICKUP(h,x qua physical))(JandK (PICKUP(h, y qua physical))(PICKUP(h, z qua physical)), where x, y and z are free variables of type JbookK. For future reference, we use P [x, y, z] to refer to J[threed books [Fred [picked up t1]]]K. Finally we have: J[28a]K = The type of all the evidence that there exist x, y, z in JBookK such that (the type of all of the evidence that x qua physical and y qua physical and z qua physical are distinct and Σ( PICKUP(h, x qua physical)) (Σ( PICKUP (h, y qua physical)) ( PICKUP (h, z qua physical)))). 2. Similarly for (28b) we have: J[threed books [Fred [mastered t1]]]K = The type of all the evidence that x qua informational and y qua informational and z qua informational are distinct and JandK (MASTER(h,x qua informational))(JandK (MASTER(h, y qua informational))(MASTER(h, z qua informational)), where x, y and z are free variables of type JbookK. For future reference, we refer to J[threed books [Fred [mastered t1]]]K as M[x, y, z]. J[(28b)]K = The type of all the evidence that there exist x, y, z in JBookK such that (the type of all of the evidence that x qua informational and y qua informational and z qua informational are distinct and Σ( MASTER(h, x qua informational)) (Σ( MASTER (h, y qua informational)) ( MASTER (h, z qua informational)))). 3. Computation of J(28c)K The syntactic structure of (28c) is as follows: (30) threei books threed books Fred picked up t1 and threed books Fred mastered t1 Note that the traces in the subtrees are the same. That is why they both have the same name t1. In contrast, the syntactic structure of the sentence "Fred picked up three books and Fred mastered three books" is as follows29: (31) threei books threed books Fred picked up t1 and threei books threed books Fred mastered t2 Now we can compute the semantic value of (28c) as follows: To make the following computations more readable, we call the subtree to the right of and in (30), treea and the one on the left, treeb. Jtreeb and treeaK = Σ JtreeaK JtreebK = Σ(P [x, y, z]) (M[x, y, z]) J(28c)K = Jthreei booksK (Jtreeb and treeaK) = The type of all the evidence that there exist x, y, z in JBookK such that (Jtreeb and treeaK) = The type of all the evidence that there exist x, y, z in JBookK such that (Σ(P [x, y, z])(M[x, y, z])) = The type of all the evidence that there exist x, y, z in JBookK such that Σ (the type of all of the evidence that x qua physical and y qua physical and z qua physical are distinct and Σ( PICKUP(h, x qua physical)) (Σ( PICKUP (h, y qua physical)) ( PICKUP (h, z qua physical)))) (the type of all the evidence that x qua informational and y qua informational and z qua informational are distinct and Σ( MASTER(h, x qua informational)) (Σ( MASTER (h, y qua informational)) ( MASTER (h, z qua informational)))) 7.5 Comparison The inadequacy of approaches in [8] and [5] can be resolved if they use the rule of existential closure as it is used in the analysis we just gave. That is, for copredication sentences, if the same syntactic structure as in section (7.4) is used, then in terms of adequacy there is no difference between [8], [5] and our approach. The advantage, however can be best described by the following remark in [39]: . . . Intuitively, there is another problem with the notion of complex argument as a product from which the simple constituent types can be retrieved via projections. Take for example the word book: the theories coercing bookP.I into either bookP or bookI loose an important aspect of the meaning of book, which becomes either a bare "physical object" or a bare "information". In order to talk about meaning of book, both components have to be present. We can manipulate with books 29The semantic value of the sentence shown in (31) is as follow: J(31)K = Σ J(28a)K J28bK; note that the variables in J(28b)K are not bound by J(28a)K the same way as we do with some general physical object, we can for example carry, drop or throw them by the virtue of them being subtypes of "physical object" and we can formalize this neatly in logic or a type theory. But where does the rest of the meaning of book go? Objects can be manipulated by casting their type into an appropriate type or, as we want to argue here, by virtue of types that constitute that object. In other words, we need a notion of structured meaning. Objects can be "transformed" or viewed from different perspective without loosing any of their meaning components. We are arguing against casting more complex types into simpler ones and losing information in the process. To illustrate the point that the above quotation wants to accentuate, consider the following minimal example30; Assume that the type Book is a subtype of the types Physical and Informational (as it is the case in [8]): 1 c l a s s Phys i ca l { 2 pub l i c f l o a t Weight ; 3 } 4 c l a s s In fo rmat i ona l { 5 pub l i c S t r ing Author ; 6 } 7 8 c l a s s Book extends Phys ica l , In f o rmat i ona l { 9 10 } We define the book Iliad as the following: 1 Book I l i a d = new Book ( ) ; 2 I l i a d . Author = "Homer" ; 3 I l i a d . Weight = 2 ; Now assume we have a function that receives as an input an object of type Physical and another one that requires its input to be an informational object: 1 void somefunct ion ( Phys i ca l phy s i c a l ) 2 { 3 . . . 4 } 5 void someother funct ion ( In fo rmat i ona l i n f o rmat i ona l ) 6 { 7 . . . 8 } We pass the book Iliad, defined above, to the function somefunction as the following: 1 Phys i ca l I l i a d p h y s i c a l = ( Phys i ca l ) I l i a d ; 2 somefunct ion ( I l i a d p h y s i c a l ) ; Now if we want to access informational properties of Iliad within the function somefunction we need to first map the Iliadphysical back to Iliad and then we need to map the Iliad to an object of Informational: 1 void somefunct ion ( Phys i ca l phy s i c a l ) 2 { 3 . . . 4 i f ( t h i s i s abook ( phy s i c a l ) ) 5 { 30The syntax of the code is that of Java except for the fact that Java does not support multiple inheritance in the sense that we are using it in the example. 6 Book book = (Book ) phy s i c a l ; 7 In f o rmat i ona l i n f o rmat i ona l = ( In fo rmat i ona l ) book ; 8 someother funct ion ( i n f o rmat i ona l ) ; 9 } 10 . . . 11 } Therefore when we have the object Iliadphysical, the informational properties of the book have been lost. We have to do two mappings, one from Physical to Book and the other from Book to Informational, to get to the informational properties. In contrast, in the identity type model, the information is never lost when going from an object to its aspects. As it is discussed in section (7.3), an object b of type book can be viewed from different perspectives as: (32) a. b qua physical = b−1p ○ f(bp) ○ b−1i ○ f−1(bi). b. b qua Informational = b−1i ○ f−1(bi) ○ b−1p ○ f(bp). Therefore b qua physical and b qua Informational do not lose any of the meaning components of b. The difference between the two "transformations" is precisely the difference between the perspectives, reflected here in the order of the components in (30). For convenience, we call the four components in qua physical the followings respectively: p,q,r and s. Now, to access informational properties within the function somefunction we can do the following: 1 void somefunct ion ( Phys i ca l phy s i c a l ) 2 { 3 . . . 4 i f ( t h i s i s abook ( phy s i c a l ) ) 5 { 6 Phys i ca l p$q$r$s = phys i c a l ; 7 someother funct ion ( r$s$p$q ) ; 8 } 9 . . . 10 } Another option, a less efficient but implementaion-wise simpler one, would be to cast the physical object directly to an informational object: 1 void somefunct ion ( Phys i ca l phy s i c a l ) 2 { 3 . . . 4 i f ( t h i s i s abook ( phy s i c a l ) ) 5 { 6 In f o rmat i ona l i n f o rmat i ona l = ( In fo rmat i ona l ) phy s i c a l ; 7 someother funct ion ( i n f o rmat i ona l ) ; 8 } 9 . . . 10 } Note that the physical object could not be transformed to an informational object if it was the physical aspect of something that did not have an information aspect as well. 8 Conclusion In pure intensional type theory, identity types need not be subject to UIP. This fact together with a homotopical interpretation of identity types in homotopy type theory provides a justification for modeling common nouns as identifications of their aspects. We showed that this model, while being simple, is able to successfully handle a semantically complex phenomenon, namely copredication when it involves individuation. Our solution relies on an analysis of numerical quantifiers which is inspired by Heim's treatment of indefinites, and an approach to meaning in formal semantics, which establishes that the denotation of a semantically interpretable sentence is a type, and the sentence is true iff its type is not empty. The type of a sentence is then envisaged as the collection of all the proofs, witnesses or evidence that the sentence is true. We showed that in this framework, copredication can be modeled with no need to subtypes and the complexities they bring about. 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