Hrushovski originated the study of “flat” stable structures in constructing a new strongly minimal set and a stable 0-categorical pseudoplane. We exhibit a set of axioms which for collections of finite structure with dimension function δ give rise to stable generic models. In addition to the Hrushovski examples, this formalization includes Baldwin's almost strongly minimal non-Desarguesian projective plane and several others. We develop the new case where finite sets may have infinite closures with respect to the dimension function (...) δ. In particular, the generic structure need not be ω-saturated and so the argument for stability is significantly more complicated. We further show that these structures are “flat” and do not interpret a group. (shrink)

We study structures equipped with generic predicates and/or automorphisms, and show that in many cases we obtain simple theories. We also show that a bounded PAC field is simple. 1998 Published by Elsevier Science B.V. All rights reserved.

A study of smooth classes whose generic structures have simple theory is carried out in a spirit similar to Hrushovski 147; Simplicity and the Lascar group, preprint, 1997) and Baldwin–Shi 1). We attach to a smooth class K0, of finite -structures a canonical inductive theory TNat, in an extension-by-definition of the language . Here TNat and the class of existentially closed models of =T+,EX, play an important role in description of the theory of the K0,-generic. We (...) show that if M is the K0,-generic then MEX. Furthermore, if this class is an elementary class then Th=Th). The investigations by Hrushovski and Pillay , provide a general theory for forking and simplicity for the nonelementary classes, and using these ideas, we show that if K0,, where {,*}, has the joint embedding property and is closed under the Independence Theorem Diagram then EX is simple. Moreover, we study cases where EX is an elementary class. We introduce the notion of semigenericity and show that if a K0,-semigeneric structure exists then EX is an elementary class and therefore the -theory of K0,-generic is near model complete. By this result we are able to give a new proof for a theorem of Baldwin and Shelah 1359). We conclude this paper by giving an example of a generic structure whose first-order theory is simple. (shrink)

In this article ideas from Kit Fine’s theory of arbitrary objects are applied to questions regarding mathematical structuralism. I discuss how sui generis mathematical structures can be viewed as generic systems of mathematical objects, where mathematical objects are conceived of as arbitrary objects in Fine’s sense.

Let L be a finite relational language and α=(αR:R ∈ L) a tuple with 0 < αR ≤1 for each R ∈ L. Consider a dimension function $ \delta _\alpha (A) = \left| A \right| - \sum\limits_{R \in L} {\alpha {\mathop{\rm Re}\nolimits} R(A)} $ where each eR(A) is the number of realizations of R in A. Let $K_\alpha $ be the class of finite structures A such that $\delta _\alpha (X) \ge 0$ 0 for any substructure X of A. (...) We show that the theory of the generic model of $K_\alpha $ is AE-axiomatizable for any α. (shrink)

The article discusses the issue of how to categorize video games—not the medium of video games, but individual video games. As a lead in to this discussion, the article discusses video game specificity and genericity and moves on to genre theory. On the basis of this discussion, a cognitive experientialist genre framework is sketched, which incorporates both general points from genre theory and theories more specific to the video game domain. The framework is illustrated through a brief example. One virtue (...) of the framework is that it offers a way to bridge the gap between game ontology and player experience; a brief conclusion discusses how the breadth of this gap may depend upon player biographies and also outlines how further work may proceed. (shrink)

We construct an ab initio generic structure for a predimension function with a positive rational coefficient less than or equal to 1 which is unsaturated and has a superstable non-ω-stable theory.

We show that any relational generic structure whose theory has finite closure and amalgamation over closed sets is stable CM-trivial with weak elimination of imaginaries.

We show that any relational generic structure whose theory has finite closure and amalgamation over closed sets is stable CM-trivial with weak elimination of imaginaries.

We prove that each ∀1 free amalgamation class K over a finite relational language L admits a countable generic structure M isometrically embedding all countable structuresin K relative to a fixed metric. We expand L by infinitely many binary predicates expressingdistance, and prove that the resulting expansion of K has a model companion axiomatizedby the first-order theory of M. The model companion is non-finitely axiomatizable, evenover a strong form of the axiom scheme of infinity.

We show that if a class K of finite relational structures is closed under quasi-substructures, then there is no saturated K-generic structure that is superstable but not ω -stable.

Let L be a countable relational language. Baldwin asked whether there is an ab initio generic L-structure which is superstable but not ω-stable. We give a positive answer to his question, and prove that there is no ab initio generic L-structure which is superstable but not ω-stable, if L is finite and the generic is saturated.

We show that the N₀-categorical structures produced by Hrushovski's predimension construction with a control function fit neatly into Shelah's $SOP_n $ hierarchy: if they are not simple, then they have SOP₃ and NSOP₄. We also show that structures produced without using a control function can be undecidable and have SOP.

We prove that for any simple theory which is constructed via Fräissé-Hrushovski method, if the forking independence is the same as the d-independence then the stable forking property holds.

Many theories of kind representation suggest that people posit internal, essence-like factors that underlie kind membership and explain properties of category members. Across three studies (N = 281), we document the characteristics of an alternative form of construal according to which the properties of social kinds are seen as products of structural factors: stable, external constraints that obtain due to the kind’s social position. Internalist and structural construals are similar in that both support formal explanations (i.e., “category member has property (...) P due to category membership C”), generic claims (“Cs have P”), and the generalization of category properties to individual category members when kind membership and social position are confounded. Our findings thus challenge these phenomena as signatures of internalist thinking. However, once category membership and structural position are unconfounded, different patterns of generalization emerge across internalist and structural construals, as do different judgments concerning category definitions and the dispensability of properties for category membership. We discuss the broader implications of these findings for accounts of formal explanation, generic language, and kind representation. (shrink)

The standard view amongst philosophers of language and linguists is that the logical form of generics is quantificational and contains a covert, unpronounced quantifier expression Gen. Recently, some theorists have begun to question the standard view and rekindle the competing proposal, that generics are a species of kind-predication. These theorists offer some forceful objections to the standard view, and new strategies for dealing with the abundance of linguistic evidence in favour of the standard view. I respond to these objections and (...) show that their strategies fail. I offer a novel argument in favour of the standard view that I call the binder argument. The upshot of this argument is that if one rejects the existence of Gen, then one is committed to rejecting the existence of covert structure in general. (shrink)

We prove that for any simple theory which is constructed via Fräissé-Hrushovski method, if the forking independence is the same as the d-independence then the stable forking property holds.

It is shown how certain generic extensions of a fine structural model in the sense of Mitchell and Steel [MiSt] can be reorganized as relativizations of the model to the generic object. This is then applied to the construction of Steel's core model for one Woodin cardinal [St] and its generalizations.

For a supersimple SU-rank 1 theory T we introduce the notion of a generic elementary pair of models of T . We show that the theory T* of all generic T-pairs is complete and supersimple. In the strongly minimal case, T* coincides with the theory of infinite dimensional pairs, which was used in 1184–1194) to study the geometric properties of T. In our SU-rank 1 setting, we use T* for the same purpose. In particular, we obtain a characterization (...) of linearity for SU-rank 1 structures by giving several equivalent conditions on T*, find a “weak” version of local modularity which is equivalent to linearity, show that linearity coincides with 1-basedness, and use the generic pairs to “recover” projective geometries over division rings from non-trivial linear SU-rank 1 structures. (shrink)

LetMbe a countably infinite ω-categorical structure. Consider Aut(M) as a complete metric space by definingd(g, h) = Ω{2−n:g(xn) ≠h(xn) org−1(xn) ≠h−1(xn)} where {xn:n∈ ω} is an enumeration ofMAn automorphism α ∈ Aut(M) is generic if its conjugacy class is comeagre. J. Truss has shown in [11] that if the set P of all finite partial isomorphisms contains a co-final subset P1closed under conjugacy and having the amalgamation property and the joint embedding property then there is a generic automorphism. (...) In the present paper we give a weaker condition of this kind which is equivalent to the existence of generic automorphisms. Really we give more: a characterization of the existence of generic expansions (defined in an appropriate way) of an ω-categorical structure. We also show that Truss' condition guarantees the existence of a countable structure consisting of automorphisms ofMwhich can be considered as an atomic model of some theory naturally associated toM. We do it in a general context of weak models for second-order quantifiers.The author thanks Ludomir Newelski for pointing out a mistake in the first version of Theorem 1.2 and for interesting discussions. Also, the author is grateful to the referee for very helpful remarks. (shrink)

Consensus has it that generic sentences such as “Dogs bark” and “Birds fly” contain, at the level of logical form, an unpronounced generic operator: Gen. On this view, generics have a tripartite structure similar to overtly quantified sentences such as “Most dogs bark” and “Typically, birds fly”. I argue that Gen doesn’t exist and that generics have a simple bipartite structure on par with ordinary atomic sentences such as “Homer is drinking”. On my view, the subject terms of (...) generics are kind-referring. The interesting truth conditions characteristic of generics arise from the interesting ways in which kinds inherit properties from their members. (shrink)

Let T be a complete, model complete o-minimal theory extending the theory RCF of real closed ordered fields in some appropriate language L. We study derivations δ on models ℳ⊧T. We introduce the no...

This article is concerned with the structure of monetary denominations of economic value. Marx and Simmel analyze this structure by means of references to objects of mere catallactic validity. These objects are ontologically atypical insofar as they are particulars of the genus commodity. Understanding money through generic particulars elucidates the conceptual link between money as a unit of account and money as a means of payment. This initially perplexing idea captures a fundamental characteristic of money without committing to either (...) a commodity theory or a claim theory of money. A modification of the notion ‘commodity’ allows for a conception of money as a generic particular that is consistent with contemporary accounts of money as abstract purchasing power residing in different forms of liabilities and claims denominated in a common quantitative scale. (shrink)

This paper examines the generic structure and underpinnings of Xenophon's Lacedaimonion Politeia. The Lac. has frequently been regarded as a praise or defence of Sparta yet its rhetoric and narrative structure bear little resemblance to contemporary practices for composing encomia or defense speeches. Although this does not preclude an encomiastic or defensive purpose, an examination of the type of rhetoric Xenophon employs and the narrative patterns and structures in the work reveal different generic affiliations, showing that the (...) Lac., like many of Xenophon’s other writings, is a hybrid work with features belonging to politeia- literature and philosophical enquiry. Further, careful examination, in particular, of the way Xenophon makes use of imaginary interlocutors suggests that praise cannot have been the aim of this treatise. (shrink)

We compare two different notions of generic expansions of countable saturated structures. One kind of genericity is related to existential closure, and another is defined via topological properties and Baire category theory. The second type of genericity was first formulated by Truss for automorphisms. We work with a later generalization, due to Ivanov, to finite tuples of predicates and functions. Let $N$ be a countable saturated model of some complete theory $T$ , and let $(N,\sigma)$ denote an expansion (...) of $N$ to the signature $L_{0}$ which is a model of some universal theory $T_{0}$ . We prove that when all existentially closed models of $T_{0}$ have the same existential theory, $(N,\sigma)$ is Truss generic if and only if $(N,\sigma)$ is an e-atomic model. When $T$ is $\omega$ -categorical and $T_{0}$ has a model companion $T_{\mathrm {mc}}$ , the e-atomic models are simply the atomic models of $T_{\mathrm {mc}}$. (shrink)

In this article a dialectical model for practical reasoning within a community, based on the Generic/Actual Argument Model (GAAM) is advanced and its application to deliberative dialogue discussed. The GAAM, offers a dynamic template for structuring knowledge within a domain of discourse that is connected to and regulated by a community. The paper demonstrates how the community accepted generic argument structure acts to normatively influence both admissible reasoning and the progression of dialectical reasoning between participants. It is further (...) demonstrated that these types of deliberation dialogues supported by the GAAM comply with criteria for normative principles for deliberation, specifically, Alexy’s rules for discourse ethics and Hitchcock’s Principles of Rational Mutual Inquiry. The connection of reasoning to the community in a documented and transparent structure assists in providing best justified reasons, principles of deliberation and ethical discourse which are important advantages for reasoning communities. (shrink)

While opinions on the semantic analysis of generics vary widely, most scholars agree that generics have a quasi-universal flavor. However, there are cases where generics receive what appears to be an existentialinterpretation. For example, B's response is true, even though only theplatypus and the echidna lay eggs: (1) A: Birds lay eggs. B: Mammals lay eggs too. In this paper I propose a uniform account of the semantics of generics,which accounts for their quasi-existential readings as well as for their more (...) familiar quasi-universal ones. Generics are focus-sensitiveoperators: their domain is restricted by a set of alternatives, which may be provided by focus. I claim that, unlike otherfocus-sensitive operators, generics may, but do not have to, associate with focus. When alternatives are introduced, either by focus or by other means, generics get their usual quasi-universal readings. But when no alternatives are introduced, quasi-existential readings result.I argue that generics, unlike adverbs of quantification, do not introduce tripartite structures directly, but are initially interpreted as cases ofdirect kind predication. Only when this interpretation fails to make sense, the phonologically null generic quantifier is derived, and tripartite structures result. This two-level interpretation has the effect that while adverbs of quantification require focus to determine which elements go to the restrictor and which to the nuclear scope, and hence must associate with focus, generics do not, and hence may fail to associate with focus, resulting in quasi-existential readings. (shrink)

Let TP be the theory obtained by adding a generic predicate to an o-minimal theory T. We prove that if T admits elimination of imaginaries, then TP also admits elimination of imaginaries.

We define a generic Vopěnka cardinal to be an inaccessible cardinal \ such that for every first-order language \ of cardinality less than \ and every set \ of \-structures, if \ and every structure in \ has cardinality less than \, then an elementary embedding between two structures in \ exists in some generic extension of V. We investigate connections between generic Vopěnka cardinals in models of ZFC and the number and complexity of \-Suslin (...) sets of reals in models of ZF. In particular, we show that ZFC + is equiconsistent with ZF + \\) where \ is the pointclass of all \-Suslin sets of reals, and also with ZF + \\) + \\) where \ is the least ordinal that is not a surjective image of the reals. (shrink)

We define a generic Vopěnka cardinal to be an inaccessible cardinal \ such that for every first-order language \ of cardinality less than \ and every set \ of \-structures, if \ and every structure in \ has cardinality less than \, then an elementary embedding between two structures in \ exists in some generic extension of V. We investigate connections between generic Vopěnka cardinals in models of ZFC and the number and complexity of \-Suslin (...) sets of reals in models of ZF. In particular, we show that ZFC + is equiconsistent with ZF + \\) where \ is the pointclass of all \-Suslin sets of reals, and also with ZF + \\) + \\) where \ is the least ordinal that is not a surjective image of the reals. (shrink)

Recently several philosophers have argued that racial, gender, and other social generic generalizations should be avoided given their propensity to promote essentialist thinking, obscure the social nature of categories, and contribute to oppression. Here I argue that a general prohibition against social generics goes too far. Given that the truth of many generics require regularities or systematic rather than mere accidental correlations, they are our best means for describing structural forms of violence and discrimination. Moreover, their accuracy, their persistence (...) in the face of counterexamples, and features of the contemporary socio-political context make generics useful linguistic tools in social justice projects. (shrink)

We study notions of genericity in models of, inspired by lines of inquiry initiated by Chatzidakis and Pillay and continued by Dolich, Miller and Steinhorn in general model‐theoretic contexts. These papers studied the theories obtained by adding a “random” predicate to a class of structures. Chatzidakis and Pillay axiomatized the theories obtained in this way. In this article, we look at the subsets of models of which satisfy the axiomatization given by Chatzidakis and Pillay; we refer to these subsets (...) in models of as CP‐generics. We study a more natural property, called strong CP‐genericity, which implies CP‐genericity. We use an arithmetic version of Cohen forcing to construct (strong) CP‐generics with various properties, including ones in which every element of the model is definable in the expansion, and, on the other extreme, ones in which the definable closure relation is unchanged. (shrink)

We continue the study of the connection between the “geometric” properties of SU -rank 1 structures and the properties of “generic” pairs of such structures, started in [8]. In particular, we show that the SU-rank of the theory of generic pairs of models of an SU -rank 1 theory T can only take values 1 , 2 or ω, generalizing the corresponding results for a strongly minimal T in [3]. We also use pairs to derive the (...) implication from pseudolinearity to linearity for ω -categorical SU -rank 1 structures, established in [7], from the conjecture that an ω -categorical supersimple theory has finite SU -rank, and find a condition on generic pairs, equivalent to pseudolinearity in the general case. (shrink)

A generic computation of a subsetAof ℕ is a computation which correctly computes most of the bits ofA, but which potentially does not halt on all inputs. The motivation for this concept is derived from complexity theory, where it has been noticed that frequently, it is more important to know how difficult a type of problem is in the general case than how difficult it is in the worst case. When we study this concept from a recursion theoretic point (...) of view, to create a transitive relationship, we are forced to consider oracles that sometimes fail to give answers when asked questions. Unfortunately, this makes working in the generic degrees quite difficult. Indeed, we show that generic reduction is$\Pi _1^1$―complete. To help avoid this difficulty, we work with the generic degrees of density-1 reals. We demonstrate how an understanding of these degrees leads to a greater understanding of the overall structure of the generic degrees, and we also use these density-1 sets to provide a new a characterization of the hyperartithmetical Turing degrees. (shrink)

This paper examines a type of discourse structure we here call ‘generic passages’. We argue that generic passages should be analyzed as sequences of generic sentences, each sentence containing its own GEN operator (Krifka et al. 1995). The GEN operators produce tripartite matrix/restrictor structures; the main discourse connection among the sentences is that the restrictor produced by each sentence in the sequence has as its contents the information in the matrix produced by the previous sentence in (...) the discourse. We also argue that an identity of reference times is required for this process to occur. In the end generic passages are a natural product of the interaction of generic operators in sentences with independently- established principles structuring ordinary extensional narrative. (shrink)

This article addresses the question which structures occur as fixed structures of stable structures with a generic automorphism. In particular we give a Galois theoretic characterization. Furthermore, we prove that any pseudofinite field is the fixed field of some model ofACFA, any one-free pseudo-differentially closed field of characteristic zero is the fixed field of some model ofDCFA, and that any one-free PAC field of finite degree of imperfection is the fixed field of some model ofSCFA.

Recent literature has suggested that generics can harbor and propagate worrying ideologies in a manner which is often not appreciated by speakers. In this article, I argue that the use of generics to convey information about mental illness is unhelpful, whether the knowledge structure conveyed by the generic is 'accurate' or not. Inaccurate generics contribute to insidious forms of social stereotyping and stigma by encouraging us to simplistically generalize characteristics found in very few category members to other members of (...) that kind.Yet, even where the knowledge structure underlying the generic is accurate, generics remain an unhelpful way of talking about mental illness. This is because... (shrink)

This paper describes a method for analyzing a corpus of descriptions collected through micro-phenomenological interviews. This analysis aims at identifying the structure of the singular experiences which have been described, and in particular their diachronic structure, while unfolding generic experiential structures through an iterative approach. After summarizing the principles of the micro-phenomenological interview, and then describing the process of preparation of the verbatim, the article presents on the one hand, the principles and conceptual devices of the analysis method (...) and on the other hand several dimensions of the analysis process: the modes of structural unfolding of generic structures, the mutual guidance of the processes of structural and experiential unfolding, the tracking of analysis processes, and finally the assessment of analysis results. (shrink)

I use generic embeddings induced by generic normal measures on that can be forced to exist if κ is an indestructibly weakly compact cardinal. These embeddings can be applied in order to obtain the forcing axioms in forcing extensions. This has consequences in : The Singular Cardinal Hypothesis holds above κ, and κ has a useful Jónsson-like property. This in turn implies that the countable tower works much like it does when κ is a Woodin limit of Woodin (...) cardinals. One consequence is that every set of reals in the Chang model is Lebesgue measurable and has the Baire Property, the Perfect Set Property and the Ramsey Property. So indestructible weak compactness has effects on cardinal arithmetic high up and also on the structure of sets of real numbers, down low, similar to supercompactness. (shrink)