We study Łoś's theorem in a choiceless context. We introduce some variants of Łoś's theorem. These variants seem weaker than Łoś's theorem, but we prove that these are equivalent to Łoś's theorem.
A formal system called cologic is proposed for the study of compacta. A counterpart of countable model theory is developed for this system, and it is applied to model theory of the pseudo-arc.
In this paper we introduce an axiomatization of Büchi arithmetic, i.e., of the elementary theory of natural numbers in the language with addition and function $V_p(a) = p^k$ such that $p^k | a$ and $p^{k + 1} \nmid a$.
Abstract Active matter with continuous energy injection that exhibits various nonequilibrium emergent behaviors, such as swarming and motility induced phase separation, has been extensively studied in the past decades. Achieving desired patterns and phases in fabricating functional materials by assembling active matter is a rising and challenging direction. Nevertheless, the ossibility of a stably ordered structure of active matter remains elusive. Toward this goal, the interplay between the active force and the volume exclusion provides a new way to manipulate mechanical stability. Here, we demonstrate a new type of active, two dimensional (2D) pseudocrystal system consisting of arrays of active rods. The pseudocrystals with tetratic array demonstrate robust stability against the thermal noise. Increasing the active force leads to a phase transition from pseudocrystal to swarming via shear melting. In the traveling pseudocrystals, on the contrary, the synchronized movement of active rods reduces internal stresses and enhances the stability of pseudocrystals. Topological defects quickly propagate in the traveling pseudocrystals and assist the stability. The present framework provides innovative insights into potentially new designs and manipulations of active materials. PACS numbers:
El asesinato de George Floyd en Minneapolis (Estados Unidos) ha desatado múltiples manifestaciones sociales antirracistas en distintos países del mundo, las cuales han adquirido diferentes formatos: marchas, disturbios, pintadas callejeras, militancia hashtag a partir del lema #BlackLiveMatters y el accionar contra diferentes estatuas de personajes históricos polémicos. Dichos monumentos, conmemoraciones a, principalmente, esclavistas y colonizadores, han sido pintados, mutilados o derribados en señal de protesta, pero también como un modo de disputa por los sentidos y las memorias legitimadas en el espacio público, que, además, tiene como antecedente las manifestaciones en Chile a fines de 2019.
We present a description of the (non-modular) commutator, inspired by that of Kearnes in~\cite[p.~930]{MR1358491}, that provides a simple recipe for computing the commutator.
This article presents an analysis of the LGBTI Pride celebrations (lesbian, gay, transsexual, bisexual and intersex) in Costa Rica between 2003 and 2016, using journalistic documents as primary sources of information. It is argued that these celebrations can be understood as social movements that seek to achieve legal, cultural and in some cases structural equality. The different modalities that these celebrations have had are established, and the paradoxes arising from their dynamics are emphasized. It is argued that in Pride celebration there is a mixture of celebration and political demands, a tension as to the “appropriate” form of representation and the short, medium and long term objectives. As a conclusion, civil rights become the central discursive thrust along all the festivals and marches.
El objetivo de este trabajo es establecer una correspondencia entre lo bello y lo sublime en la obra “El caminante sobre el mar de nubes” de Caspar D. Friedrich. En efecto, nos proponemos dilucidar los encuentros y desencuentros de la experiencia estética de esta obra estudiada desde la perspectiva de Immanuel Kant.
A Q-set is an uncountable set of reals all of whose subsets are relative $G_δ$ sets. We prove that, for an arbitrary uncountable cardinal kappa, there is consistently a Q-set of size $κ$ whose square is not Q. This answers a question of A. Miller.
In this paper, we give a constructive method for linear extensions of Zadeh's fuzzy orders. We also characterize Zadeh's fuzzy orders by their linear extensions.
We prove in ZF a recursive-theoretic characterization of the Topological Vaught Conjecture by revisiting the fact that orbits in Polish $G$-spaces are Borel sets.
The most recent wave of applications of logic to operator algebras is a young and rapidly developing field. This is a snapshot of the current state of the art.
We describe the countable ordinals in terms of iterations of Mostowski collapsings. This gives a proof-theoretic bound of definable countable ordinals in the Zermelo-Fraenkel's set theory ZF.
In this paper we give an algebraic characterization of the projections lattice of $M_n(\mathbb C)$ and we extend it to the case of $B(H)$, with $H$ separable Hilbert space.
The paper is an extended version of the talk in the Logic Colloquium-2000 at Paris. We discuss a series of results and problems around Hrushovski's construction of counter-examples to the Trichotomy conjecture.