The class of geometric surgical theories is examined. The main theorem is that every stable theory that is interpretable in a geometric surgical theory is superstable of finite U-rank.

This paper is concerned with extensions of geometric stability theory to some nonelementary classes. We prove the following theorem:Theorem. Let [Formula: see text] be a large homogeneous model of a stable diagram D. Let p, q ∈ SD(A), where p is quasiminimal and q unbounded. Let [Formula: see text] and [Formula: see text]. Suppose that there exists an integer n < ω such that [Formula: see text] for any independent a1, …, an∈ P and finite subset C (...) ⊆ Q, but [Formula: see text] for some independent a1, …, an, an+1∈ P and some finite subset C ⊆ Q.Then [Formula: see text] interprets a group G which acts on the geometry P′ obtained from P. Furthermore, either [Formula: see text] interprets a non-classical group, or n = 1,2,3 and•If n = 1 then G is abelian and acts regularly on P′.•If n = 2 the action of G on P′ is isomorphic to the affine action of K ⋊ K* on the algebraically closed field K.•If n = 3 the action of G on P′ is isomorphic to the action of PGL2(K) on the projective line ℙ1(K) of the algebraically closed field K.We prove a similar result for excellent classes. (shrink)

We study the theory of the structure induced by parameter free formulas on a “dense” algebraically independent subset of a model of a geometric theory T. We show that while being a trivial geometric theory, inherits most of the model theoretic complexity of T related to stability, simplicity, rosiness, the NIP and the NTP2. In particular, we show that T is strongly minimal, supersimple of SU‐rank 1, has the NIP or the NTP2 exactly when (...) has these properties. We show that if T is superrosy of thorn rank 1, then so is, and that the converse holds if T satisfies acl = dcl. (shrink)

The aim of this communication is to consider morphological processes in sociology, mainly through the study of the stability of forms of sociality. At the same time, it aims to study the regulation of constraints, related to an increasingly conflictual environment, through political organization. We use a specific theoretical framework: the catastrophe theory developed by René Thom in topology, further developed by Claude Bruter from a physics point of view, and reworked by Jacques Viret in biology. The idea (...) is to show the existence of archetypal processes organizing social forms. (shrink)

§1. Introduction. With Hrushovski's proof of the function field Mordell-Lang conjecture [16] the relevance of geometric stability theory to diophantine geometry first came to light. A gulf between logicians and number theorists allowed for contradictory reactions. It has been asserted that Hrushovski's proof was simply an algebraic argument masked in the language of model theory. Another camp held that this theorem was merely a clever one-off. Still others regarded the argument as magical and asked whether such (...) sorcery could unlock the secrets of a wide coterie of number theoretic problems.In the intervening years each of these prejudices has been revealed as false though such attitudes are still common. The methods pioneered in [16] have been extended and applied to a number of other problems. At their best, these methods have been integrated into the general methods for solving diophantine problems. Moreover, the newer work suggests limits to the application of model theory to diophantine geometry. For example, all such known applications are connected with commutative algebraic groups. This need not be an intrinsic restriction, but its removal requires serious advances in the model theory of fields. (shrink)

Certain basic concepts of geometrical stability theory are generalized to a class of closure operators containing algebraic closure. A specific case of a generalized closure operator is developed which is relevant to Vaught's conjecture. As an application of the methods, we prove THEOREM A. Let G be a superstable group of U-rank ω such that the generics of G are locally modular and Th(G) has few countable models. Let G - be the group of nongeneric elements of G, (...) G + = G o + G - . Let Π= {q ∈ S( $\emptyset$ ): U(q) $A \subset M$ such that M is almost atomic over A ∪ (G + ∩ M) $\cup \bigcup_{p\in \Pi}$ p(M). (shrink)

In recent work, the authors have established the group configuration theorem for simple theories, as well as some of its main applications from geometric stability theory, such as the binding group theorem, or in the $\omega$-categorical case, the characterization of the forking geometry of a finitely based non-trivial locally modular regular type as projective geometry over a finite field and the equivalence of pseudolinearity and local modularity. The proof necessitated an extension of the model-theoretic framework to include (...) almost hyperimaginaries, and the study of polygroups. (shrink)

It is stated in many text books that the any metric appearing in general relativity should be locally Lorentzian i.e. of the type η μ ν =diag (1,−1,−1,−1) this is usually presented as an independent axiom of the theory, which can not be deduced from other assumptions. The meaning of this assertion is that a specific coordinate (the temporal coordinate) is given a unique significance with respect to the other spatial coordinates. In this work it is shown that the (...) above assertion is a consequence of requirement that the metric of empty space should be linearly stable and need not be assumed. (shrink)

This paper presents some finite combinatorics of set systems with applications to model theory, particularly the study of dependent theories. There are two main results. First, we give a way of producing lower bounds on $\mathrm {VC}_{\mathrm {ind}}$-density and use it to compute the exact $\mathrm {VC}_{\mathrm {ind}}$-density of polynomial inequalities and a variety of geometric set families. The main technical tool used is the notion of a maximum set system, which we juxtapose to indiscernibles. In the second (...) part of the paper we give a maximum set system analogue to Shelah’s characterization of stability using indiscernible sequences. (shrink)

We study Lascar strong types and Galois types and especially their relation to notions of type which have finite character. We define a notion of a strong type with finite character, the so-called Lascar type. We show that this notion is stronger than Galois type over countable sets in simple and superstable finitary AECs. Furthermore, we give an example where the Galois type itself does not have finite character in such a class.

Using methods of geometric stability , we determine the structure of Abelian groups definable in ACFA, the model companion of fields with an automorphism. We also give general bounds on sets definable in ACFA. We show that these tools can be used to study torsion points on Abelian varieties; among other results, we deduce a fairly general case of a conjecture of Tate and Voloch on p-adic distances of torsion points from subvarieties.

In this paper we deal with the model theory of differentially closed fields of characteristic zero with finitely many commuting derivations. First we observe that the only known lower bound for the Lascar rank of types in differentially closed fields, announced in a paper of McGrail, is false. This gives us a new class of regular types which are orthogonal to fields. Then we classify the subgroups of the additive group of Lascar rank omega with differential-type 1 which are (...) nonorthogonal to fields. The last parts consist of an analaysis of the quotients of the heat variety. We show that the generic type of such a quotient is locally modular. Finally, we answer a question of Phylliss Cassidy about the existence of certain Jordan-Holder type series in the negative. (shrink)

We study the notion of weak one-basedness introduced in recent work of Berenstein and Vassiliev. Our main results are that this notion characterizes linearity in the setting of geometric þ-rank 1structures and that lovely pairs of weakly one-based geometric þ-rank 1 structures are weakly one-based with respect to þ-independence. We also study geometries arising from infinite-dimensional vector spaces over division rings.

We initiate a geometric stability study of groups of the form G/G00, where G is a 1-dimensional definably compact, definably connected, definable group in a real closed field M. We consider an enriched structure M′ with a predicate for G00 and check 1-basedness or non-1-basedness for G/G00, where G is an additive truncation of M, a multiplicative truncation of M, SO2(M) or one of its truncations; such groups G/G00 are now interpretable in M′. We prove that the only (...) 1-based groups are those where G is a sufficiently “big” multiplicative truncation, and we relate the results obtained to valuation theory. In the last section we extend our results to ind-hyperdefinable groups constructed from those above. (shrink)

We introduce a realist, unextravagant interpretation of quantum theory that builds on the existing physical structure of the theory and allows experiments to have definite outcomes but leaves the theory’s basic dynamical content essentially intact. Much as classical systems have specific states that evolve along definite trajectories through configuration spaces, the traditional formulation of quantum theory permits assuming that closed quantum systems have specific states that evolve unitarily along definite trajectories through Hilbert spaces, and our interpretation (...) extends this intuitive picture of states and Hilbert-space trajectories to the more realistic case of open quantum systems despite the generic development of entanglement. We provide independent justification for the partial-trace operation for density matrices, reformulate wave-function collapse in terms of an underlying interpolating dynamics, derive the Born rule from deeper principles, resolve several open questions regarding ontological stability and dynamics, address a number of familiar no-go theorems, and argue that our interpretation is ultimately compatible with Lorentz invariance. Along the way, we also investigate a number of unexplored features of quantum theory, including an interesting geometrical structure—which we call subsystem space—that we believe merits further study. We conclude with a summary, a list of criteria for future work on quantum foundations, and further research directions. We include an appendix that briefly reviews the traditional Copenhagen interpretation and the measurement problem of quantum theory, as well as the instrumentalist approach and a collection of foundational theorems not otherwise discussed in the main text. (shrink)

In this paper, it is shown that if [Formula: see text] is a complete type of Lascar rank at least 2, in the theory of differentially closed fields of characteristic zero, then there exists a pair of realisations [Formula: see text], [Formula: see text] such that p has a nonalgebraic forking extension over [Formula: see text]. Moreover, if A is contained in the field of constants then p already has a nonalgebraic forking extension over [Formula: see text]. The results (...) are also formulated in a more general setting. (shrink)

In The Equilibrium Manifold, noted economic scholar and major contributor to the theory of general equilibrium Yves Balasko argues that, contrary to what many textbooks want readers to believe, the study of the general equilibrium model did not end with the existence and welfare theorems of the 1950s. These developments, which characterize the modern phase of the theory of general equilibrium, led to what Balasko calls the postmodern phase, marked by the reintroduction of differentiability assumptions and the application (...) of the methods of differential topology to the study of the equilibrium equation. Balasko's rigorous study demonstrates the central role played by the equilibrium manifold in understanding the properties of the Arrow-Debreu model and its extensions. Balasko argues that the tools of differential topology articulated around the concept of equilibrium manifold offer powerful methods for studying economically important issues, from existence and uniqueness to business cycles and economic fluctuations. After an examination of the theory of general equilibrium's evolution in the hundred years between Walras and Arrow-Debreu, Balasko discusses the properties of the equilibrium manifold and the natural projection. He highlights the important role of the set of no-trade equilibria, the structure of which is applied to the global structure of the equilibrium manifold. He also develops a geometric approach to the study of the equilibrium manifold. Applications include stability issues of adjustment dynamics for out-of-equilibrium prices, the introduction of price-dependent preferences, and aspects of time and uncertainty in extensions of the general equilibrium model that account for various forms of market frictions and imperfections. Special effort has been made at reducing the mathematical technicalities without compromising rigor. The Equilibrium Manifold makes clear the ways in which the postmodern" developments of the Arrow-Debreu model improve our understanding of modern market economies. (shrink)

This essay develops a joint theory of rational (all-or-nothing) belief and degrees of belief. The theory is based on three assumptions: the logical closure of rational belief; the axioms of probability for rational degrees of belief; and the so-called Lockean thesis, in which the concepts of rational belief and rational degree of belief figure simultaneously. In spite of what is commonly believed, this essay will show that this combination of principles is satisfiable (and indeed nontrivially so) and that (...) the principles are jointly satisfied if and only if rational belief is equivalent to the assignment of a stably high rational degree of belief. Although the logical closure of belief and the Lockean thesis are attractive postulates in themselves, initially this may seem like a formal “curiosity”; however, as will be argued in the rest of the essay, a very reasonable theory of rational belief can be built around these principles that is not ad hoc and that has various philosophical features that are plausible independently. In particular, this essay shows that the theory allows for a solution to the Lottery Paradox, and it has nice applications to formal epistemology. The price that is to be paid for this theory is a strong dependency of belief on the context, where a context involves both the agent's degree of belief function and the partitioning or individuation of the underlying possibilities. But as this essay argues, that price seems to be affordable. (shrink)

In this commentary on Rotts paper Stability, Strength and Sensitivity: Converting Belief into Knowledge, I discuss two problems of the stability theory of knowledge which are pointed out by Rott. I conclude that these problems offer no reason for rejecting the stability theory, but might be grounds for deviating from the standard AGM account of belief revision which Rott presupposes.

We initiate a systematic investigation of the abstract elementary classes that have amalgamation, satisfy tameness, and are stable in some cardinal. Assuming the singular cardinal hypothesis, we prove a full characterization of the stability cardinals, and connect the stability spectrum with the behavior of saturated models.We deduce that if a class is stable on a tail of cardinals, then it has no long splitting chains. This indicates that there is a clear notion of superstability in this framework.We also (...) present an application to homogeneous model theory: for [Formula: see text] a homogeneous diagram in a first-order theory [Formula: see text], if [Formula: see text] is both stable in [Formula: see text] and categorical in [Formula: see text] then [Formula: see text] is stable in all [Formula: see text]. (shrink)

In this paper we compare Leitgeb’s stability theory of belief and Spohn’s ranking-theoretic account of belief. We discuss the two theories as solutions to the lottery paradox. To compare the two theories, we introduce a novel translation between ranking functions and probability functions. We draw some crucial consequences from this translation, in particular a new probabilistic belief notion. Based on this, we explore the logical relation between the two belief theories, showing that models of Leitgeb’s theory correspond (...) to certain models of Spohn’s theory. The reverse is not true. Finally, we discuss how these results raise new questions in belief theory. In particular, we raise the question whether stability is rightly thought of as a property pertaining to belief. (shrink)

This book presents a coherent and systematic exposition of the mathematical theory of the problems of optimization and stability. Both of these are topics central to economic analysis since the latter is so much concerned with the optimizing behaviour of economic agents and the stability of the interaction processes to which this gives rise. The topics covered include convexity, mathematical programming, fixed point theorems, comparative static analysis and duality, the stability of dynamic systems, the calculus of (...) variations and optimal control theory. The authors present a more detailed and wide-ranging discussion of these topics than is to be found in the few books which attempt a similar coverage. Although the text deals with fairly advanced material, the mathematical prerequisites are minimised by the inclusion of an integrated mathematical review designed to make the text self-contained and accessible to the reader with only an elementary knowledge of calculus and linear algebra. A novel feature of the book is that it provides the reader with an understanding and feel for the kinds of mathematical techniques most useful for dealing with particular economic problems. This is achieved through an extensive use of a broad range of economic examples.This is suitable for use in advanced undergraduate and postgraduate courses in economic analysis and should in addition prove a useful reference work for practising economists. (shrink)

InStabilizing Dynamics Roy Weintraub provides a history of stability theory from the work of Hicks and Samuelson in the late 1930s to the Gale and Scarf counterexamples in the 1960s. Unlike his earlier work in the history of general equilibrium theory this recent contribution is not an attempt to fit the Walrasian program into the narrow framework of some particular philosophy of natural science. Rather, the theme inStabilizing Dynamicsis broadly social constructivist. Simply put, the constructivist view of (...) science is “that scientific knowledge itself is constructed socially, in communities of scientists: Knowledge is constructed, not found”. (shrink)

Despite its age, quantum theory still suffers from serious conceptual difficulties. To create clarity, mathematical physicists have been attempting to formulate quantum theory geometrically and to find a rigorous method of quantization, but this has not resolved the problem. In this article we argue that a quantum theory recursing to quantization algorithms is necessarily incomplete. To provide an alternative approach, we show that the Schrödinger equation is a consequence of three partial differential equations governing the time evolution (...) of a given probability density. These equations, discovered by Madelung, naturally ground the Schrödinger theory in Newtonian mechanics and Kolmogorovian probability theory. A variety of far-reaching consequences for the projection postulate, the correspondence principle, the measurement problem, the uncertainty principle, and the modeling of particle creation and annihilation are immediate. We also give a speculative interpretation of the equations following Bohm, Vigier and Tsekov, by claiming that quantum mechanical behavior is possibly caused by gravitational background noise. (shrink)

Harry Eckstein’s long-standing (but ever-changing) hypothesis that a nation’s political stability is a function of “congruence” between the “authority patterns” exhibited by the government and those displayed by nearly every sort of institution under that government’s aegis involved a highly complex politico-psychological theory. As a result, it was quite difficult either to confirm or disconfirm. While there have been a number of suggested revisions that apparently simplify his thesis, they suffer either from vagueness or a failure to take (...) democracy to be a system that requires an actual commitment to majoritarianism. In this paper a revision is offered that utilizes a small number of completely dichotomous variables that are easily subject to empirical tests. This revised theory (of “consonance” rather than congruence) is also explicitly majoritarian, enabling it to shed light on the essential nature of democratic regimes. (shrink)

La tentativa de pensar los seres vivos en términos geométricos y topológicos forma parte del programa de investigación llevado a cabo por René Thom . Anteriormente la Psicología de la Forma había investigado la estabilidad estructural en la percepción en analogía con procesos biológicos y neurológicos. La idea no es, pues, nueva, se encuentra explícitamente formulada en los tratados de D’Arcy Thompson y, antes, en las morfologías estáticas de Descartes y en la Metamorfosis de las Plantas y la Teoría de (...) los Colores de Goethe. La afirmación de que en otras culturas, con independencia de lugar y fecha, los seres humanos y entre ellos las inteligencias más primitivas conciben sistemas básicamente convergentes que representan otras y distintas formas de entender y practicar "ciencia", constituyen el marco temático del presente trabajo.The attempt of understanding living beings in geometrical and topological terms is a part of the investigation project undertaken by René Thom . Earlier the Gestalt psychology had cross-examined the structural stability in the analogy perception within biological and neurogical processes. The idea, far from being a new one, can be found explicitly formulated both in the D’Arcy Thompson’s treatises and in the Descartes´ static morphologies and in Goethe´s Metamorphosis of Plants and Theory of Colors as well. The statement that in other cultures, regardless the place and date, human beings –even more primitive intelligences– are capable of conceiving basically convergent systems which are supposed to represent quite another different forms of understanding and practising "science", is the theoretical framework of the present paper. (shrink)

ArgumentIn his Philosophia practica universalis, Christian Wolff proposes a “mathematical” theory of moral action that includes his statements on the Aesopian fable. As a sort of moral example, Wolff claims, the fable is an appropriate means to influence human conduct because it conveys general truths to intuition. This didactic concept is modeled on the geometrical figure: Just as students intuit mathematical demonstrations by looking at figures on a blackboard, one can learn how to execute complex actions by listening to (...) a fable. Wolff's “scientific” fable theory met with an ambivalent reception. Lessing, who in his fable treatises re-translates Wolff's suggestions into the conceptual framework of poetics, interprets the geometric model as a stylistic ideal. The famous passage on Homer's successive descriptions in Lessing's Laokoon can be seen as another attempt to apply the representational model of geometry to literature. Herder, reading Wolff in a way that might be called deconstructive, replaces Wolff's geometric theory of poetry by a poetic anthropology of geometry. (shrink)

We study expansions of an algebraically closed field K or a real closed field R with a linearly independent subgroup G of the multiplicative group of the field or the unit circle group \\), satisfying a density/codensity condition. Since the set G is neither algebraically closed nor algebraically independent, the expansion can be viewed as “intermediate” between the two other types of dense/codense expansions of geometric theories: lovely pairs and H-structures. We show that in both the algebraically closed field (...) and real closed field cases, the resulting theory is near model complete and the expansion preserves many nice model theoretic conditions related to the complexity of definable sets such as stability and NIP. (shrink)

Introduction to sensory psychology, by C. Mueller.--Some reflections on brain and mind, by R. Brain.--In search of the engram, by K. Lashly.--Cerebral organization and behavior, by R. W. Sperry.--Relations between the central nervous system and the peripheral organs, by E. von Holst.--Effects of the Gestalt revolution, by J. E. Hochberg.--Seeing in depth, by R. L. Gregory.--The stimulus variables for visual depth perception, by J. J. Gibson.--The elaboration of the universe, by J. Piaget.--Visual perception approached by the method of stabilized images, (...) by R. M. Pritchard, W. Heron, and D. O. Hebb.--Philosophy as rigorous science, by E. Husserl.--The "sensation" as a unit of experience, by M. Merleau-Ponty.--The phenomenology of perception: perceptual implications, by A. Gurwitsch.--The expression of thinking, by E. W. Straus.--The concept of group and the theory of perception, by E. Cassirer.--Norm and pathology of I-world relations, by E. W. Straus.--The metaphysical in man, by M. Merleau-Ponty.--Cultural differences in the perception of geometric illusions, by M. H. Segall, D. T. Campbell, and M. J. Herskovits.--The interpretive cortex, by W. Penfield.--Recovery from early blindness: a case study, by R. L. Gregory and J. G. Wallace.--Visual disturbances after perceptual isolation, by W. Heron, B. K. Doane, and T. H. Scott. (shrink)

In summary, many extant definitions of the niche concept are based on the geometric metaphor which represents the niche as an object embedded in a geometric space. There are several difficulties with this approach; the activities of organisms are not fully described, certain attributes of the functional aspect of the niche are not represented, the life cycles of organisms are not described, and the heuristic value of the concept diminishes with increasing dimensionality.An alternative and complementary approach to the (...) niche is the linguistic metaphor. This approach is based on the explanatory objective to explain the assembly of the ecosystems of successional seres from species pools and abiotic environmental factors. The linguistic metaphor suggests that a theory of ecosystem assembly is a generative grammar that associates particular species with environmental features. The niche of a particular species is defined in terms of the rules of a generative-transformational grammar used to derive an hierarchically organized description of that species. This approach also has conceptual difficulties: (1) empirically testing competence theories and distinguishing possible and impossible objects (e.g. species and ecosystems) are difficult, (2) evolutionary processes are difficult to incorporate, (3) the mathematical tools associated with grammars do not have the range of applicability of the mathematical tools associated with the geometric metaphor, and (4) the productions (hierarchical trees) of a grammar are not easily visualized.The geometric and linguistic metaphors of the niche should be viewed as complementary pictures of the same object. The geometric representation is most adept at describing community dynamics and stability, niche overlap, and organism response to abiotic environments. The linguistic metaphor represents well organism activities, niche dynamics, and ecosystem assembly. (shrink)

A systematic and comprehensive introduction to the study of nonlinear dynamical systems, in both discrete and continuous time, for nonmathematical students and researchers working in applied fields. An understanding of linear systems and the classical theory of stability are essential although basic reviews of the relevant material are provided. Further chapters are devoted to the stability of invariant sets, bifurcation theory, chaotic dynamics and the transition to chaos. In the final two chapters the authors approach the (...) subject from a measure-theoretical point of view and compare results to those given for the geometrical or topological approach of the first eight chapters. Includes about one hundred exercises. A Windows-compatible software programme called DMC, provided free of charge through a website dedicated to the book, allows readers to perform numerical and graphical analysis of dynamical systems. Also available on the website are computer exercises and solutions to selected book exercises. See www.cambridge.org/economics/resources. (shrink)

We analyze the geometric foundations of classical Yang-Mills theory by studying the relationships between internal relativity, locality, global/local invariance, and background independence. We argue that internal relativity and background independence are the two independent defining principles of Yang-Mills theory. We show that local gauge invariance -heuristically implemented by means of the gauge argument- is a direct consequence of internal relativity. Finally, we analyze the conceptual meaning of BRST symmetry in terms of the invariance of the gauge fixed (...) theory under general local gauge transformations. (shrink)

Spekkens has introduced a toy theory (Spekkens in Phys. Rev. A 75(3):032110, 2007) in order to argue for an epistemic view of quantum states. I describe a notation for the theory (excluding certain joint measurements) which makes its similarities and differences with the quantum mechanics of stabilizer states clear. Given an application of the qubit stabilizer formalism, it is often entirely straightforward to construct an analogous application of the notation to the toy theory. This assists calculations within (...) the toy theory, for example of the number of possible states and transformations, and enables superpositions to be defined for composite systems. (shrink)

I see model theory as becoming increasingly detached from set theory, and the Tarskian notion of set-theoretic model being no longer central to model theory. In much of modern mathematics, the set-theoretic component is of minor interest, and basic notions are geometric or category-theoretic. In algebraic geometry, schemes or algebraic spaces are the basic notions, with the older “sets of points in affine or projective space” no more than restrictive special cases. The basic notions may be (...) given sheaf-theoretically, or functorially. To understand in depth the historically important affine cases, one does best to work with more general schemes. The resulting relativization and “transfer of structure” is incomparably more flexible and powerful than anything yet known in “set-theoretic model theory”.It seems to me now uncontroversial to see the fine structure of definitions as becoming the central concern of model theory, to the extent that one can easily imagine the subject being called “Definability Theory” in the near future.Tarski's set-theoretic foundational formulations are still favoured by the majority of model-theorists, and evolution towards a more suggestive language has been perplexingly slow. None of the main texts uses in any nontrivial way the language of category theory, far less sheaf theory or topos theory. Given that the most notable interactions of model theory with geometry are in areas of geometry where the language of sheaves is almost indispensable, this is a curious situation, and I find it hard to imagine that it will not change soon, and rapidly. (shrink)

It is shown how to identify potential signatures of noncommutative geometry within the decay spectrum of a muon in orbit near the event horizon of a microscopic Schwarzschild black hole. This possibility follows from a re-interpretation of Moffat’s nonsymmetric theory of gravity, first published in Phys. Rev. D 19:3554, 1979, where the antisymmetric part of the metric tensor manifests the hypothesized noncommutative geometric structure throughout the manifold. It is further shown that for a given sign convention, the predicted (...) signatures counteract the effects of curvature-induced muon stabilization predicted by Singh and Mobed in Phys. Rev. D 79:024026, 2009. While it is unclear whether evidence for noncommutative geometry may become observable anytime soon, this approach at least provides a useful direction for future quantum gravity research based on the ideas presented here. (shrink)

We study the class of weakly locally modular geometric theories introduced in [4], a common generalization of the classes of linear SU-rank 1 and linear o-minimal theories. We find new conditions equivalent to weak local modularity: "weak one-basedness", absence of type definable "almost quasidesigns", and "generic linearity". Among other things, we show that weak one-basedness is closed under reducts. We also show that the lovely pair expansion of a non-trivial weakly one-based ω-categorical geometric theory interprets an infinite (...) vector space over a finite field. (shrink)

The topic of moral diversity is not only prevalent in contemporary moral and political philosophy, it is also practically relevant. Moral diversity, however, poses a significant challenge for moral theory building. John Thrasher, in his discussion of public reason theory, which includes social contract theory, argues that if one seriously considers the goal of moral constructivism and considerations of representation and stability, then moral diversity poses an insurmountable problem for most public reason theories. I agree with (...) Thrasher that moral diversity poses a significant challenge for orthodox multistage social contract theories. In fact, I even add a further problem for such theories under the assumption of deep moral diversity. Nevertheless, I argue that my recently developed multilevel social contract theory overcomes these problems. I focus on some of the underexplored features of this theory to show that multilevel social contract theory offers one conceptually coherent and plausible way to render social contract theory viable and relevant for modern diverse societies. (shrink)