The "space" of Lascar strong types, on some sort and relative to a given complete theory T, is in general not a compact Hausdorff topological space. We have at least three aims in this paper. The first is to show that spaces of Lascar strong types, as well as other related spaces and objects such as the Lascar group Gal L of T, have well-defined Borel cardinalities. The second is to compute the Borel cardinalities of the known examples as well (...) as of some new examples that we give. The third is to explore notions of definable map, embedding, and isomorphism, between these and related quotient objects. We also make some conjectures, the main one being roughly "smooth if and only if trivial". The possibility of a descriptive set-theoretic account of the complexity of spaces of Lascar strong types was touched on in the paper [E. Casanovas, D. Lascar, A. Pillay and M. Ziegler, Galois groups of first order theories, J. Math. Logic1 305–319], where the first example of a "non-G-compact theory" was given. The motivation for writing this paper is partly the discovery of new examples via definable groups, in [A. Conversano and A. Pillay, Connected components of definable groups and o-minimality I, Adv. Math.231 605–623; Connected components of definable groups and o-minimality II, to appear in Ann. Pure Appl. Logic] and the generalizations in [J. Gismatullin and K. Krupiński, On model-theoretic connected components in some group extensions, preprint, arXiv:1201.5221v1]. (shrink)

We generalize the model theory of small profinite structures developed by Newelski to the case of compact metric spaces considered together with compact groups of homeomorphisms and satisfying the existence of m-independent extensions (we call them compact e-structures). We analyze the relationships between smallness and different versions of the assumption of the existence of m-independent extensions and we obtain some topological consequences of these assumptions. Using them, we adopt Newelski's proofs of various results about small profinite structures to compact e-structures. (...) In particular, we notice that a variant of the group configuration theorem holds in this context. A general construction of compact structures is described. Using it, a class of examples of compact e-structures which are not small is constructed. It is also noticed that in an m-stable compact e-structure every orbit is equidominant with a product of m-regular orbits. (shrink)

We analyze model-theoretic connected components in extensions of a given group by abelian groups which are defined by means of 2-cocycles with finite image. We characterize, in terms of these 2-cocycles, when the smallest type-definable subgroup of the corresponding extension differs from the smallest invariant subgroup. In some situations, we also describe the quotient of these two connected components. Using our general results about extensions of groups together with Matsumoto–Moore theory or various quasi-characters considered in bounded cohomology, we obtain new (...) classes of examples of groups whose smallest type-definable subgroup of bounded index differs from the smallest invariant subgroup of bounded index. This includes the first known example of a group with this property found by Conversano and Pillay, namely the universal cover of [Formula: see text], as well as various examples of different nature, e.g. some central extensions of free groups or of fundamental groups of closed orientable surfaces. As a corollary, we get that both non-abelian free groups and fundamental groups of closed orientable surfaces of genus [Formula: see text], expanded by predicates for all subsets, have this property, too. We also obtain a variant of the example of Conversano and Pillay for [Formula: see text] instead of [Formula: see text], which was not accessible by the previously known methods. (shrink)

We give examples of (i) a simple theory with a formula (with parameters) which does not fork over [Formula: see text] but has [Formula: see text]-measure 0 for every automorphism invariant Keisler measure [Formula: see text] and (ii) a definable group [Formula: see text] in a simple theory such that [Formula: see text] is not definably amenable, i.e. there is no translation invariant Keisler measure on [Formula: see text]. We also discuss paradoxical decompositions both in the setting of discrete groups (...) and of definable groups, and prove some positive results about small theories, including the definable amenability of definable groups. (shrink)

Che gli esseri umani siano i soli animali capaci di ridere e piangere può essere messo in dubbio, ma che siano gli unici a sviluppare degli strumenti a questo scopo, non può esserlo. Tragedia e commedia, i due fronti dell’arte drammatica codificati da Aristotele nella "Poetica", sono proprio questi strumenti. La difficoltà a conferire un significato univoco a questi due magmatici termini, è sintomatica. In questo breve scritto tento di identificare la ragione di questa difficoltà e proporre un’ipotesi di lavoro (...) per risolverla, o per lo meno approcciarla. (shrink)

The facts aboutsuch, then, indicate not just thatsuch is a pro-adjective, but also that binding conditions apply broadly to pro-ADJs and pro-CNs, as well as to a wide range of pro-arguments. If this is true, the CN binding process accomplished by rules (40) and (41) might better be expressed in a system that uses a Cooper (1979) store mechanism. In fact, Stump (p. 144) notes that this could easily be done. Meanings of the type of∨ P n could be stored, (...) just as NP meanings are, until an appropriate binding CN phrase was encountered. Binding conditions would simply require that a∨ P n meaning not come out of storage until the derivation had emerged from its governing category. The behavior of the pro-adjectivesuch suggests that an expression of any category, if it is legitimately translatable as a variable, may be a fullfledged proform; many principles and mechanisms described to account for the widely studied pronouns in fact apply to nonargument categories. (shrink)

Using payment to recruit research subjects is a common practice, but it raises ethical concerns that coercion or undue inducement could potentially compromise participants’ informed consent. This is the first national study to explore the attitudes of IRB members and other human subjects protection professionals concerning whether payment of research participants constitutes coercion or undue influence, and if so, why. The majority of respondents expressed concern that payment of any amount might influence a participant’s decisions or behaviors regarding research participation. (...) Respondents expressed greater acceptance of payment as reimbursement or compensation than as an incentive to participate in research, and most agreed that subjects are coerced if the offer of payment makes them participate when they otherwise would not or when the offer of payment causes them to feel that they have no reasonable alternative but to participate . Views about undue influence were similar. We conclude that human subjects protection professionals hold expansive and inconsistent views about coercion and undue influence that may interfere with the recruitment of research participants and impede valuable research. (shrink)

In some young children brought by their parents for diagnosis of acute life-threatening events investigations suggested imposed apnoea as the cause rather than spontaneous occurrence. Covert video surveillance of the cot in which the baby was monitored allowed confirmation or rebuttal of this diagnosis. That parents were not informed of the video recording was essential for diagnosis and we assert ethically justifiable as the child was the patient to whom a predominant duty of care was owed. The procedure also avoids (...) the risk of separation of child from parent on inadequate information. (shrink)

Although the equally pervasive and abstract concept of space has generated a vast body of disciplines, time, and the related idea of "becoming" (transforming, ...