The Homeostatic Property Cluster (HPC) account of natural kinds has become popular since it was proposed by Richard Boyd in the late 1980s. Although it is often taken as a defining natural kinds as such, it is easy enough to see that something's being a natural kind is neither necessary nor sufficient for its being an HPC. This paper argues that it is better not to understand HPCs as defining what it is to be a natural kind but instead as (...) providing the ontological realization of (some) natural kinds. (shrink)

At Home in the Universe. According to the modified joke, Kauffman's method is to begin any scientific investigation with the statement "Consider an NK Boolean network." Indeed, throughout At Home in the Universe just about every real-world problem gets translated into a toy-world problem involving NK Boolean networks. As with Carnap's formal languages, NK Boolean networks have the advantage of complete logical precision. But they also suffer the disadvantage of losing touch with reality. And it is this disadvantage which ultimately (...) proves the undoing of Kauffman's project. (shrink)

T‐bet and Eomes are two related transcription factors (TFs) that regulate the differentiation of cytotoxic lymphocytes such as Natural Killer (NK) cells and CD8 T cells. Recent genome‐wide analyses suggest they have complementary roles in instructing the transcriptional program of NK cells, although their DNA binding sites appear to be very similar. In this essay, we discuss the mechanisms that could specify their action, addressing their expression profile, the cofactors they interact with, as well as their roles in the epigenetic (...) regulation of chromatin accessibility. Based on the recent literature on these TFs, we propose different models to describe how they regulate gene expression in NK cells at steady state, or in the context of activation or exhaustion. We also discuss recent findings in the field of CD8 T cell differentiation and residency, where Eomes and T‐bet appear to be major regulators, and the parallels that can be drawn between mechanisms of NK and CD8 T cell differentiation and trafficking. (shrink)

Discussion of the cognitive division of labor has usually made very little contact with relevant materials from other disciplines, including theoretical biology, management science, and design theory. This article draws on these materials to consider some unavoidable conundrums faced by any attempt to present a particular way of dividing tasks among a labor team as the uniquely rational way of doing this, given the interdependence of the underlying evaluative standards by which the products of a system of division of labor (...) will be judged. Divisions of labor will typically cut across these interdependencies in ways which leave the outcomes of a process of labor hostage to path dependencies and suboptimalities. Some attempts to avoid these results are shown to be unsuccessful. All these difficulties are compounded by the fact that, in many cases, the division of labor has to be constructed over a ground of values that is itself being constructed simultaneously with the products which they are invoked to assess. Key Words: risk spreading • interdependency • NK fitness landscapes • complexity • epistasis • Kuhn • modularity • path dependency. (shrink)

LK is much more difficult than NK, and to make matters worse, Gentzen's intention is still unclear when it comes to that system (LK). -/- The second and third volumes of the series titled What is LK? conduct the detailed survey of each inference-figure in a toe-to-toe way, as it were, which most mathematicians looked through. -/- The present volume, Vol.3, looks deeper into those operational inference-figures which concerns propositional logic.

… the supreme end, the happiness of all mankind (Kr VA851/NKS 665).The law concerning punishment is a Categorical Imperative; and woe to him who rummages around in the winding paths of a theory of happiness, looking for some advantage to be gained by releasing the criminal from punishment or by reducing the amount of it (Rl.A196/B226, 6:331; Ladd, 100).

Philosophers disagree over whether dispositions can be intrinsically finked or masked. Choi suggests that there are no clear, relevant differences between cases where intrinsic finks would be absurd and those where they seem plausible, and as a result rejects them wholesale. Here, I highlight two features of dispositional properties which, when considered together, provide a plausible explanation for when dispositions can be subject to intrinsic finks and when not.

A minimal formula is a formula which is minimal in provable formulas with respect to the substitution relation. This paper shows the following: (1) A β-normal proof of a minimal formula of depth 2 is unique in NJ. (2) There exists a minimal formula of depth 3 whose βη-normal proof is not unique in NJ. (3) There exists a minimal formula of depth 3 whose βη-normal proof is not unique in NK.

The identity of a natural kind can be construed in terms of its causal profile. This conception is more appropriate to science than two alternatives. The identity of a natural kind is not determined by one causal role because one natural kind can have many causal roles and several functions and because some functions are shared by different kinds. Furthermore, the microstructuralist thesis is wrong: The identity of certain natural kinds is not determined by their microstructure. It is true that (...) if A and B have the same microstructural composition then a sample of a chemical substance A is of the same chemical substance as a sample of B. However, the reverse does not hold. It is not the case that if a sample of a chemical substance A is of the same chemical substance as a sample of B then A and B have the same microstructural composition. This is because a macroscopic NK can be “multiconstituted” by different microstructures. (shrink)

This is a presentation about joint work between Hector Zenil and Jean-Paul Delahaye. Zenil presents Experimental Algorithmic Theory as Algorithmic Information Theory and NKS, put together in a mixer. Algorithmic Complexity Theory defines the algorithmic complexity k(s) as the length of the shortest program that produces s. But since finding this short program is in general an undecidable question, the only way to approach k(s) is to use compression algorithms. He shows how to use the Compress function in Mathematica to (...) give an idea about the compressibility of various sequences. However, the idea of applying a compression algorithm breaks down for very short sequences. This is true not only for the Compress function, but also for any other compression algorithm. Zenil's approach is to construct a metric of algorithmic complexity for short sequences from scratch. He defines the algorithmic probability as the probability that an arbitrary program produces a sequence. The basic idea is to run a whole class of computational devices such as Turing Machines or Cellular Automata, and compute the distributions of the sequences they generate. Zenil presents a comparison of frequency distributions of sequences generated by 2-state 3-color Turing Machines and 2-color radius 1 Cellular Automata. He also compared these distributions to distributions found in data from the real world, and found that not only there is correlation across different systems, but also that the distributions are rather stable, and the difference between the distributions in abstract systems and real-world data can be attributed to noise. In his paper Zenil elaborates on the nature of the noise he has encountered. Zenil conjectures that the correlation distances between different systems decreases with a larger number of steps, and converge in the infinite limit case. (shrink)

We need to distinguish two sorts of natural kinds, scientific and common NKs, because the notion of NK, which has to satisfy demands at three different levels—ontological, semantic and epistemological—, is subject to two incompatible sets of constraints. In order to prove this, I focus on the much-discussed case of jade. In the first part of the paper, I show that the current accounts are unsatisfactory because they are inconsistent. In the process, I explain why LaPorte’s analysis of “jade” as (...) a vernacular NK-term with an open-texture meaning does not offer a way out. Using a reductio ad absurdum argument, I conclude that according to the main tenets of NK-term theories, today’s “jade” has to be an NK-term, and jade thereby an NK. In the second part of the paper, I argue for this conclusion in a positive manner. First, I present a series of thought experiments demonstrating that today’s “jade” has the specific features of an NK-term. Then, I show that the kind that we presently call “jade” exhibits the typical ontological and epistemological features of an NK. More generally, I expound on why common NKs are more than mere classes, and why categories such as “jade” are useful in many inferences and explanations. (shrink)

The paper provides a proof-theory for a negative presentation of classical logic based on a single primitive of exclusion, generalizing the known presentation via the binary ‘nand. The completeness is established via deductive equivalence to Gentzens NK/LK systems.

This work contributes to the program of studying effective versions of “almost-everywhere” theorems in analysis and ergodic theory via algorithmic randomness. Consider the setting of Cantor space {0,1}N with the uniform measure and the usual shift. We determine the level of randomness needed for a point so that multiple recurrence in the sense of Furstenberg into effectively closed sets P of positive measure holds for iterations starting at the point. This means that for each k∈N there is an n such (...) that n,2n,…,kn shifts of the point all end up in P. We consider multiple recurrence into closed sets that possess various degrees of effectiveness: clopen, Π10 with computable measure, and Π10. The notions of Kurtz, Schnorr, and Martin-Löf randomness, respectively, turn out to be sufficient. We obtain similar results for multiple recurrence with respect to the k commuting shift operators on {0,1}Nk. (shrink)

A Ramsey statement denoted \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${n \longrightarrow (k)^2_2}$$\end{document} says that every undirected graph on n vertices contains either a clique or an independent set of size k. Any such valid statement can be encoded into a valid DNF formula RAM(n, k) of size O(nk) and with terms of size \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\left(\begin{smallmatrix}k\\2\end{smallmatrix}\right)}$$\end{document}. Let rk be the minimal n for which the statement holds. We prove that (...) RAM(rk, k) requires exponential size constant depth Frege systems, answering a problem of Krishnamurthy and Moll [15]. As a consequence of Pudlák’s work in bounded arithmetic [19] it is known that there are quasi-polynomial size constant depth Frege proofs of RAM(4k, k), but the proof complexity of these formulas in resolution R or in its extension R(log) is unknown. We define two relativizations of the Ramsey statement that still have quasi-polynomial size constant depth Frege proofs but for which we establish exponential lower bound for R. (shrink)

Trudy Mat. Inst. Steklov. Proc. Steklov Inst. Math. l2l () () ON A BOUND FOR THE COMPLEXITY OF TERMS IN THE RESOLUTION METHOD UDC 51.01 : NK ...

Most material below is ranked around the splittings of lattices of normal modal logics. These splittings are generated by nite subdirect irreducible modal algebras. The actual computation of the splittings is often a rather delicate task. Rened model structures are very useful to this purpose, as well as they are in many other respects. E.g. the analysis of various lattices of extensions, like ES5, ES4:3 etc becomes rather simple, if rened structures are used. But this point will not be touched (...) here. The variety T BA , which corresponds to S4, is congruence- distributive. Hence any every tabular extension L S4 has nite many extensions only. Around 1975 it has been proved by several authors, that also the converse is true: If L S4 has nitely many extensions only, then L is necessarely tabular. These and other results will be extended to much richer lattices. For simplicity we state the results explicitely only for the lattice N of modal logics with one modal operator. But most of them carry over literally to the lattice Nk of k-ramied normal modal logics . It is easy to construct examples of 2-ramied modal logics which are P OST-complete but not tabular. Whether this will be possible for normal modal logic seems to be an open problem. In view of results below it seems very unlikely that such examples exist. (shrink)

The papers where Gerhard Gentzen introduced natural deduction and sequent calculi suggest that his conception of logic differs substantially from the now dominant views introduced by Hilbert, Gödel, Tarski, and others. Specifically, (1) the definitive features of natural deduction calculi allowed Gentzen to assert that his classical system nk is complete based purely on the sort of evidence that Hilbert called ?experimental?, and (2) the structure of the sequent calculi li and lk allowed Gentzen to conceptualize completeness as a question (...) about the relationships among a system's individual rules (as opposed to the relationship between a system as a whole and its ?semantics?). Gentzen's conception of logic is compelling in its own right. It is also of historical interest, because it allows for a better understanding of the invention of natural deduction and sequent calculi. (shrink)