Results 141 to 150 of about 1,820 (180)
Coanalytic ultrafilter bases [PDF]
Archive for Mathematical Logic, 2021 We study the definability of ultrafilter bases on $ω$ in the sense of descriptive set theory. As a main result we show that there is no coanalytic base for a Ramsey ultrafilter, while in $L$ we can construct $Π^1_1$ P-point and Q-point bases. We also show that the existence of a $\mathbfΔ^1_{n+1}$ ultrafilter is equivalent to that of a $\mathbfΠ^1_n ...
Jonathan Schilhan
exaly +5 more sources
On ultrafilter extensions of first-order models and ultrafilter interpretations [PDF]
Archive for Mathematical Logic, 2021 There exist two known canonical types of ultrafilter extensions of first-order models; one comes from modal logic and universal algebra, another one from model theory and algebra of ultrafilters, with ultrafilter extensions of semigroups as its main precursor.
Denis I Saveliev
exaly +3 more sources
A Road to Ultrafilter Extensions [PDF]
Logic in Asia: Studia Logica Library, 2019 We propose a uniform method of constructing ultrafilter extensions from canonical models, which is based on the similarity between ultrafilters and maximal consistent sets. This method can help us understand why the known ultrafilter extensions of models for normal modal logics and for classical modal logics are so defined. We then apply this method to
exaly +3 more sources
Some of the next articles are maybe not open access.
Related searches:
Related searches:
Ukrainian Mathematical Journal, 2016
A ballean is an alternative description of a coarse structure appearing in asymptotic topology. Ultrafilters on the other hand can be thought of as structures with which to describe the Stone-Čech compactifications. In this paper the authors combine these two structures and present a number of properties of this interaction.
Protasov, I.V., Slobodianiuk, S.V.
openaire +2 more sources
A ballean is an alternative description of a coarse structure appearing in asymptotic topology. Ultrafilters on the other hand can be thought of as structures with which to describe the Stone-Čech compactifications. In this paper the authors combine these two structures and present a number of properties of this interaction.
Protasov, I.V., Slobodianiuk, S.V.
openaire +2 more sources
Proceedings of IEEE 9th Annual Conference on Structure in Complexity Theory, 2002
The fusion method (A. Wigderson, 1993) is developed by exploring its similarities with the ultraproduct construction in model theory. We use this analogy to re-prove a result of M. Sipser (1984) regarding countable circuits, in a simpler way. In the finite case this analogy allows us to give a new characterization of co-NP in terms of the CLIQUE ...
Shai Ben-David +2 more
openaire +1 more source
The fusion method (A. Wigderson, 1993) is developed by exploring its similarities with the ultraproduct construction in model theory. We use this analogy to re-prove a result of M. Sipser (1984) regarding countable circuits, in a simpler way. In the finite case this analogy allows us to give a new characterization of co-NP in terms of the CLIQUE ...
Shai Ben-David +2 more
openaire +1 more source
Thin ultrafilters and the P-hierarchy of ultrafilters
Topology and its Applications, 2020If \(\mathcal I\) is a family of subsets of some set \(X\), an ultrafilter \(u\) on \( \omega\) is an \textit{\(\mathcal I\)-ultrafilter} if, for every function \(f: \omega \to X\), there is \(U\in u\) such that \(f(U) \in I\) [\textit{J. E. Baumgartner}, J. Symb. Log. 60, No. 2, 624--639 (1995; Zbl 0834.04005)].
Machura, Michał, Starosolski, Andrzej
openaire +2 more sources
Journal of Symbolic Logic, 1972
In this paper we shall construct nonregular ultrafilters showing many of the model-theoretic properties of their regular counterparts. The crucial idea in these constructions is to replace the use of regularity by independent functions. We shall use the notation and terminology of [1], our fundamental concepts being defined as follows:Definition 1.1 ...
openaire +1 more source
In this paper we shall construct nonregular ultrafilters showing many of the model-theoretic properties of their regular counterparts. The crucial idea in these constructions is to replace the use of regularity by independent functions. We shall use the notation and terminology of [1], our fundamental concepts being defined as follows:Definition 1.1 ...
openaire +1 more source
2019
Summary: In this paper, the concept of soft ultrafilters is introduced and some of the related structures such as soft Stone-Čech compactification, principal soft ultrafilters and basis for its topology are studied.
openaire +1 more source
Summary: In this paper, the concept of soft ultrafilters is introduced and some of the related structures such as soft Stone-Čech compactification, principal soft ultrafilters and basis for its topology are studied.
openaire +1 more source
Q-ultrafilters and normal ultrafilters in B-algebras
Studia Logica, 1986The first part of the paper deals with some subclasses of B-algebras and their applications to the semantics of \(SCI_ B\), the Boolean strengthening of the sentential calculus with identity (SCI). In the second part a generalization of the McKinsey-Tarski construction of well- connected topological Boolean algebras to the class of B-algebras is given.
openaire +2 more sources