The author proved in his Ph.D. Thesis [W. Veldman, Investigations in intuitionistic hierarchy theory, Ph.D. Thesis, Katholieke Universiteit Nijmegen, 1981] that, in intuitionistic analysis, the positively Borel subsets of Baire space form a genuinely growing hierarchy: every level of the hierarchy contains sets that do not occur at any lower level. It follows from this result that there are natural examples of analytic and also of co-analytic sets that are not positively Borel. It turns out, however, that, in intuitionistic analysis, (...) one may give surprisingly different and, in some sense, much more simple examples of analytic and co-analytic sets that fail to be positively Borel. In the paper, two such examples are given. In proving them correct, one obtains new proofs of the Borel Hierarchy Theorem. Brouwer’s Continuity Principle plays a crucial role in arguments. (shrink)

R. Shore proved that every recursively enumerable set can be split into two nowhere simple sets. Splitting theorems play an important role in recursion theory since they provide information about the lattice ϵ of all r. e. sets. Nowhere simple sets were further studied by D. Miller and J. Remmel, and we generalize some of their results. We characterize r. e. sets which can be split into two effectively nowhere simple sets, and r. e. sets which can (...) be split into two r. e. non-nowhere simple sets. We show that every r. e. set is either the disjoint union of two effectively nowhere simple sets or two noneffectively nowhere simple sets. We characterize r. e. sets whose every nontrivial splitting is into nowhere simple sets, and r. e. sets whose every nontrivial splitting is into effectively nowhere simple sets. R. Shore proved that for every effectively nowhere simple set A, the lattice L* is effectively isomorphic to ϵ*, and that there is a nowhere simple set A such that L* is not effectively isomorphic to ϵ*. We prove that every nonzero r. e. Turing degree contains a noneffectively nowhere simple set A with the lattice L* effectively isomorphic to ϵ*. (shrink)

We prove conjectures of Herrmann and Stob by showing that the dense simple sets are orbit complete w.r.t. the simple sets.

We follow [8] in asking when a set of ordinals $X \subseteq \alpha$ is a countable union of sets in K, the core model. We show that, analogously to L, and X closed under the canonical Σ 1 Skolem function for K α can be so decomposed provided K is such that no ω-closed filters are put on its measure sequence, but not otherwise. This proviso holds if there is no inner model of a weak Erdős-type property.

The main aim is to extend the range of logics which solve the set-theoretic paradoxes, over and above what was achieved by earlier work in the area. In doing this, the paper also provides a link between metacomplete logics and those that solve the paradoxes, by finally establishing that all M1-metacomplete logics can be used as a basis for naive set theory. In doing so, we manage to reach logics that are very close in their axiomatization to that of the (...) logic R of relevant implication. A further aim is the use of metavaluations in a new context, expanding the range of application of this novel technique, already used in the context of negation and arithmetic, thus providing an alternative to traditional model theoretic approaches. (shrink)

Centuries ago, the principle of Occam's razor changed our world by showing simpler answers to be preferable and more often true. In Life Is Simple, scientist Johnjoe McFadden traces centuries of discoveries, taking us from a geocentric cosmos to quantum mechanics and DNA, arguing that simplicity has revealed profound answers to the greatest mysteries. This is no coincidence. From the laws that keep a ball in motion to those that govern evolution, simplicity, he claims, has shaped the universe itself. (...) And in McFadden's view, life could only have emerged by embracing maximal simplicity, making the fundamental law of the universe a cosmic form of natural selection that favors survival of the simplest. (shrink)

A set of propositional connectives is said to be functionally complete if all propositional formulae can be expressed using only connectives from that set. In this paper we give sufficient and necessary conditions for a one-element set of propositional connectives to be functionally complete. These conditions provide a simple and elegant characterization of functionally complete one-element sets of propositional connectives.

I believe that, for reasons elaborated elsewhere (Beall, 2009; Priest, 2006a, 2006b), the logic LP (Asenjo, 1966; Asenjo & Tamburino, 1975; Priest, 1979) is roughly right as far as logic goes.1 But logic cannot go everywhere; we need to provide nonlogical axioms to specify our (axiomatic) theories. This is uncontroversial, but it has also been the source of discomfort for LP-based theorists, particularly with respect to true mathematical theories which we take to be consistent. My example, throughout, is arithmetic; but (...) the more general case is also considered. (shrink)

The main results of the present paper are the following theorems: 1. There is no e ∈ ω such that for any A, B ⊆ ω, SA = Wmath image is simple in A, and if A′ [TRIPLE BOND]TB′, then SA =* SB. 2 There is an e ∈ ω such that for any A, B ⊆ ω, MA = We is incomplete maximal in A, and if A =* B, then MA [TRIPLE BOND]TMB.

An incomplete degree is cuppable if it can be joined by an incomplete degree to a complete degree. For sets fulfilling some type of simplicity property one can now ask whether these sets are cuppable with respect to a certain type of reducibilities. Several such results are known. In this paper we settle all the remaining cases for the standard notions of simplicity and all the main strong reducibilities.

In Simple Rules for a Complex World, I outlined a set of legal rules that facilitate just and efficient social interactions among individuals. Frederick Schauer's critique of my book ignores the specific implications of my system in favor of a general critique of simplicity that overlooks the dangers to liberty when complex rules confer vast discretion on public figures. He also does not refer to the nonlibertarian features of my system that allow for overcoming holdout positions. These “take and (...) pay” rules explain how a system broadly protective of private property responds to well‐known two‐person (Able‐Infirm) hypothetical of the sort advanced by G. A. Cohen, which are designed to show how claims of self‐ownership lend strong support to egalitarian outcomes. (shrink)

Einstellung effects designate the phenomenon where established routines can prevent people from finding other, possibly more efficient solutions. Here we investigate the mechanism behi...

Michael Potter presents a comprehensive new philosophical introduction to set theory. Anyone wishing to work on the logical foundations of mathematics must understand set theory, which lies at its heart. Potter offers a thorough account of cardinal and ordinal arithmetic, and the various axiom candidates. He discusses in detail the project of set-theoretic reduction, which aims to interpret the rest of mathematics in terms of set theory. The key question here is how to deal with the paradoxes that bedevil set (...) theory. Potter offers a strikingly simple version of the most widely accepted response to the paradoxes, which classifies sets by means of a hierarchy of levels. What makes the book unique is that it interweaves a careful presentation of the technical material with a penetrating philosophical critique. Potter does not merely expound the theory dogmatically but at every stage discusses in detail the reasons that can be offered for believing it to be true. Set Theory and its Philosophy is a key text for philosophy, mathematical logic, and computer science. (shrink)

This paper presents a simple decidable logic of functional dependence LFD, based on an extension of classical propositional logic with dependence atoms plus dependence quantifiers treated as modalities, within the setting of generalized assignment semantics for first order logic. The expressive strength, complete proof calculus and meta-properties of LFD are explored. Various language extensions are presented as well, up to undecidable modal-style logics for independence and dynamic logics of changing dependence models. Finally, more concrete settings for dependence are discussed: (...) continuous dependence in topological models, linear dependence in vector spaces, and temporal dependence in dynamical systems and games. (shrink)

We provide a general investigation of Logic in which the notion of a simple consequence relation is taken to be fundamental. Our notion is more general than the usual one since we give up monotonicity and use multisets rather than sets. We use our notion for characterizing several known logics (including Linear Logic and non-monotonic logics) and for a general, semantics-independent classi cation of standard connectives via equations on consequence relations (these include Girard's \multiplicatives" and \additives"). We next investigate (...) the standard methods for uniformly representing consequence relations: Hilbert type, Natural Deduction and Gentzen type. The advantages and disadvantages of using each system and what should be taken as.. (shrink)

There are indications that simple reaction time might have slowed in Western countries, based on both cohort- and multi-study comparisons. A possible limitation of the latter method in particular is measurement error stemming from methods variance, which results from the fact that instruments and experimental conditions change over time and between studies. We therefore set out to measure the simple auditory reaction time (SRT) of 7,081 individuals (2,997 males and 4,084 females) born in Sweden 1959-1985 (subjects were aged (...) between 27 and 54 years at time of measurement). Depending on cut-offs and adjustment for ageing related slowing on SRT, the data suggest that SRT has increased between 3 and 16 ms in the 27 birth years covered in the present sample. The slowing is unlikely to be explained by attrition, as evaluated by comparing the general intelligence × birth-year interactions and standard deviations for both male participants and dropouts, utilizing military conscript cognitive ability data. The present result is consistent with previous studies employing alternative methods, and may result from several synergistic factors, such as possible recent micro-evolutionary trends favouring lower g in Sweden and the effects of industrially produced neurotoxic substances on peripheral nerve conduction velocity. (shrink)

Let μ be a universal lower enumerable semi-measure . Any computable upper bound for μ can be effectively separated from zero with a constant . Computable positive lower bounds for μ can be nontrivial and allow one to construct natural examples of hypersimple sets.

This meta-study of animal semantics is anchored in two claims, seemingly creating a fuzzy mismatch, that animal utterances generally appear to be simple in structure and content variation and that animals’ communicative understanding seems disproportionally more advanced. A set of excerpted, new studies is chosen as basis to discuss whether the semantics of animal uttering and understanding can be fused into one. Studies are prioritised due to their relatively complex designs, giving priority to dynamics between syntax, semantics, pragmatics, and (...) between utterers and receivers in context. A communicational framework based on utterance theory is applied as a lens for inspection of how these aspects relate to the assumed mismatch. Inspection and discussions of the studies bring several features to surface of which five are stressed in the following. Firstly, both syntactic structures and possible semantic content are seen as lean, although richer than earlier believed, and research continues to reveal new complexities in utterances. Secondly, there is a clear willingness to broaden the perception of animals’ semantic capacity to comprehend communication both by arguing theoretically and by generating empirical research in new contexts. Thirdly, the ambition to make sense of these tendencies is still often motivated by an evolutionary search for early building blocks for verbal language, with the pro et cons that such a position can have. Fourthly, the ‘allowed’ scientific frame for studying semantic capacity among animals is extended to new fields and contexts challenging the only-in-the-wild norm. Fifthly, the dilemma of integrating uttering and understanding as aspects of an after all functional communicational system, calls for new epistemological concepts to make sense of the claimed mismatch. Affordances, abduction, life-genre, and lifeworld are suggested. (shrink)

To talk about simple concepts presupposes that the notion of concept has been aptly explicated. I argue that a most adequate explication should abandon the set-theoretical paradigm and use a procedural approach. Such a procedural approach is offered by Tichý´s Transparent Intensional Logic (TIL). Some main notions and principles of TIL are briefly presented, and as a result, concepts are explicated as a kind of abstract procedure. Then it can be shown that simplicity, as applied to concepts, is well (...) definable as a property relative to conceptual systems, each of which is determined by a finite set of simple (‘primitive’) concepts. Refinement as a method of replacing simple concepts by compound concepts is defined. (shrink)

A simple and complete proof of strong normalization for first- and second-order intuitionistic natural deduction including disjunction, first-order existence and permutative conversions is given. The paper follows the Tait–Girard approach via computability predicates and saturated sets. Strong normalization is first established for a set of conversions of a new kind, then deduced for the standard conversions. Difficulties arising for disjunction are resolved using a new logic where disjunction is restricted to atomic formulas.

The simple substitution property provides a systematic and easy method for proving a theorem from the additional axioms of intermediate prepositional logics. There have been known only four intermediate logics that have the additional axioms with the property. In this paper, we reformulate the many valued logics S' n defined in Gödel [3] and prove the simple substitution property for them. In our former paper [9], we proved that the sets of axioms composed of one prepositional variable do (...) not have the property except two of them. Here we provide another proof for this theorem. (shrink)

Engineers fine-tune the design of robot bodies for control purposes, however, a methodology or set of tools is largely absent, and optimization of morphology (shape, material properties of robot bodies, etc.) is lagging behind the development of controllers. This has become even more prominent with the advent of compliant, deformable or ”soft” bodies. These carry substantial potential regarding their exploitation for control—sometimes referred to as ”morphological computation”. In this article, we briefly review different notions of computation by physical systems and (...) propose the dynamical systems framework as the most useful in the context of describing and eventually designing the interactions of controllers and bodies. Then, we look at the pros and cons of simple vs. complex bodies, critically reviewing the attractive notion of ”soft” bodies automatically taking over control tasks. We address another key dimension of the design space—whether model-based control should be used and to what extent it is feasible to develop faithful models for different morphologies. (shrink)

In this paper, following an idea of Christophe Chalons. I propose a new kind of forcing axiom, the Maximality Principle, which asserts that any sentence varphi holding in some forcing extension $V^P$ and all subsequent extensions $V^{P\ast Q}$ holds already in V. It follows, in fact, that such sentences must also hold in all forcing extensions of V. In modal terms, therefore, the Maximality Principle is expressed by the scheme $(\lozenge \square \varphi) \Rightarrow \square \varphi$ , and is equivalent to (...) the modal theory S5. In this article. I prove that the Maximality Principle is relatively consistent with ZFC. A boldface version of the Maximality Principle, obtained by allowing real parameters to appear in φ, is equiconsistent with the scheme asserting that $V_\delta \prec V$ for an inaccessible cardinal δ, which in turn is equiconsistent with the scheme asserting that ORD is Mahlo. The strongest principle along these lines is $\square MP\!_{\!\!\!\!\!\!_{\!\!_\sim}}$ , which asserts that $MP\!_{\!\!\!\!\!\!_{\!\!_\sim}}$ holds in V and all forcing extensions. From this, it follows that $0^\#$ exists, that $x^\#$ exists for every set x, that projective truth is invariant by forcing, that Woodin cardinals are consistent and much more. Many open questions remain. (shrink)

In the last number of C.Q. Mr. A. D. Knox has drawn up a list of Theocriteans who, he suggests, ‘have all of them made the most elementary mistake’ of failing to consider the possibility at least that it is the Boy, and not the Fox, who is the subject of καθξ in Id. I. 51. From that list he will have to with-draw two names, Gow and Campbell. This construction, which Mr. Knox propounds as a novelty, had been suggested (...) by Mr. Gow in C.R. XLIV., pp. 9–10. For my part, I am not ingenious, and that syntactical possibility would no more have occurred to me independently than would Mr. Gow's three renderings of it, two of which are ‘until he sets her vinous breakfast upon a more solid basis’ and ‘until he sets her grapes on toast’; as little could I ever have thought, with Mr. Knox, of ‘the obvious necessity’ for this fox ‘of rest after a heavy meal’; still less of those further inevitable eventualities1 at which he hints with such delicacy in his quotation of Aelian V. 39. In regard to these and all such matters, to my mind ‘it were to consider too curiously to consider so.’ For even in Greek which represented for my ears some such English as ‘until she set him a-breakfastant upon the dries,’ if there was one thing with which I was completely satisfied it was with the Fox as subject; that seemed so perfectly in keeping both with the happy playfulness of the passage and with the richly idiomatic φατ as applied to a graven image of an animal. But from the fact that I criticized Mr. Gow's note it is obvious that I was familiar with his idea. (shrink)

The paper presents a simple game-theoretic model in which players decide on search procedures for a prize located in one of a set of labeled boxes. The prize is awarded to the player who finds it first. A player can decide on the number of (costly) search units he employs and on the order in which he conducts the search. It is shown that in equilibrium, the players employ an equal number of search units and conduct a completely random (...) search. The paper demonstrates that the search procedure is intrinsically inefficient. Journal of Economic Literature Classification.. (shrink)

The paper presents a simple game-theoretic model in which players decide on search procedures for a prize located in one of a set of labeled boxes. The prize is awarded to the player who finds it first. A player can decide on the number of (costly) search units he employs and on the order in which he conducts the search. It is shown that in equilibrium, the players employ an equal number of search units and conduct a completely random (...) search. The paper demonstrates that the search procedure is intrinsically inefficient. Journal of Economic Literature Classification Number: D83. (shrink)

Our aim is to show that translating the modal graphs of Moretti’s “n-opposition theory” (2004) into set theory by a suited device, through identifying logical modal formulas with appropriate subsets of a characteristic set, one can, in a constructive and exhaustive way, by means of a simple recurring combinatory, exhibit all so-called “logical bi-simplexes of dimension n” (or n-oppositional figures, that is the logical squares, logical hexagons, logical cubes, etc.) contained in the logic produced by any given modal graph (...) (an exhaustiveness which was not possible before). In this paper we shall handle explicitly the classical case of the so-called 3(3)-modal graph (which is, among others, the one of S5), getting to a very elegant tetraicosahedronal geometrisation of this logic. (shrink)

A Collective Identity Function (CIF) is a rule which aggregates personal opinions on whether an individual belongs to a certain identity into a social decision. A simple CIF is one which can be expressed in terms of winning coalitions. We characterize simple CIFs and explore various CIFs of the literature by exploiting their ability of being expressed in terms of winning coalitions. We also use our setting to introduce conditions that ensure the equal treatment of individuals as voters (...) or as outcomes. (shrink)

Let $V_\propto$ be a fixed, fully effective, infinite dimensional vector space. Let $\mathscr{L}(V_\propto)$ be the lattice consisting of the recursively enumerable (r.e.) subspaces of $V_\propto$ , under the operations of intersection and weak sum (see § 1 for precise definitions). In this article we examine the algebraic properties of $\mathscr{L}(V_\propto)$ . Early research on recursively enumerable algebraic structures was done by Rabin [14], Frolich and Shepherdson [5], Dekker [3], Hamilton [7], and Guhl [6]. Our results are based upon the more (...) recent work concerning vector spaces of Metakides and Nerode [12], Crossley and Nerode [2], Remmel [15], [16], and Kalantari [8]. In the main theorem below, we extend a result of Lachlan from the lattice E of r.e. sets to $\mathscr{L}(V_\propto)$ . We define hyperhypersimple vector spaces, discuss some of their properties and show if $A, B \in \mathscr{L}(V_\propto)$ , and A is a hyperhypersimple subspace of B then there is a recursive space C such that A + C = B. It will be proven that if $V \in \mathscr{L}(V_\propto)$ and the lattice of superspaces of V is a complemented modular lattice then V is hyperhypersimple. The final section contains a summary of related results concerning maximality and simplicity. (shrink)

In this paper, following an idea of Christophe Chalons, I propose a new kind of forcing axiom, the Maximality Principle, which asserts that any sentence φ holding in some forcing extension $V\P$ and all subsequent extensions V\P*\Qdot holds already in V. It follows, in fact, that such sentences must also hold in all forcing extensions of V. In modal terms, therefore, the Maximality Principle is expressed by the scheme $\implies\necessaryφ$, and is equivalent to the modal theory S5. In this article, (...) I prove that the Maximality Principle is relatively consistent with \ZFC. A boldface version of the Maximality Principle, obtained by allowing real parameters to appear in φ, is equiconsistent with the scheme asserting that $Vδ\elesub V$ for an inaccessible cardinal δ, which in turn is equiconsistent with the scheme asserting that $\ORD$ is Mahlo. The strongest principle along these lines is $\necessary\MPtilde$, which asserts that $\MPtilde$ holds in V and all forcing extensions. From this, it follows that 0# exists, that x# exists for every set x, that projective truth is invariant by forcing, that Woodin cardinals are consistent and much more. Many open questions remain. (shrink)

While there has been in depth discussion of many particular argumentation schemes, some lament that there is little to no theory underpinning the notion of an argumentation scheme. Here I shall argue against the utility of argument schemes, at least as a fundamental part of a complete theory of arguments. I shall also present and defend a minimalist theory of their nature—a scheme is just a set of proposition expressions and propositional functions. While simple, the theory contravenes several typical (...) desiderata of argumentation schemes such as aiding in the identification of enthymemes and keeping arguments constrained to a manageable taxonomy. So much the worse for the desiderata. Instead, I shall recommend focusing less on schemes and more on the component propositional functions. (shrink)

While there has been in depth discussion of many particular argumentation schemes, some lament that there is little to no theory underpinning the notion of an argumentation scheme. Here I shall argue against the utility of argument schemes, at least as a fundamental part of a complete theory of arguments. I shall also present and defend a minimalist theory of their nature—a scheme is just a set of proposition expressions and propositional functions. While simple, the theory contravenes several typical (...) desiderata of argumentation schemes such as (i) aiding in the identification of enthymemes and (ii) keeping arguments constrained to a manageable taxonomy. So much the worse for the desiderata. Instead, I shall recommend focusing less on schemes and more on the component propositional functions. (shrink)

The performance of a connectionist learning system on a simple problem has been described by Hinton and is briefly reviewed here: a finite set is learned from a finite collection of finite sets, and the system generalizes correctly from partial information by finding simple "features" of the environment. For comparison, a very similar problem is formulated in the Gold paradigm of discrete learning functions. To get generalization similar to the connectionist system, a non-conservative learning strategy is required. We (...) define a simple, non-conservative strategy that generalizes like the connectionist system, finding simple "features" of the environment. By placing an arbitrary finite bound on the number and complexity of the features to be found, learning can be guaranteed relative to a probabilistic criterion of success. However, this approach to induction has essentially the same problems as many others that have failed. (shrink)