1,721,081 research outputs found
Úplná vnoření a jejich modifikace
No full textMatematický ústav UKMathematical Institute of Charles UniversityFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult
The basic CSP reductions revisited
No full textNon UBCUnreviewedAuthor affiliation: Charles University in PragueFacult
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Infinite Domain Constraint Satisfaction Problem (Invited Talk)
No full textThe computational and descriptive complexity of finite domain fixed template constraint satisfaction problem (CSP) is a well developed topic that combines several areas in mathematics and computer science. Allowing the domain to be infinite provides a way larger playground which covers many more computational problems and requires further mathematical tools. I will talk about some of the research challenges and recent progress on them
Accessible set functors are universal
Full text linksummary:It is shown that every concretizable category can be fully embedded into the category of accessible set functors and natural transformations
Relational Approach to Universal Algebra
No full textTitle: Relational Approach to Universal Algebra Author: Jakub Opršal Department: Department of Algebra Supervisor: doc. Libor Barto, Ph.D., Department of Algebra Abstract: We give some descriptions of certain algebraic properties using rela- tions and relational structures. In the first part, we focus on Neumann's lattice of interpretability types of varieties. First, we prove a characterization of vari- eties defined by linear identities, and we prove that some conditions cannot be characterized by linear identities. Next, we provide a partial result on Taylor's modularity conjecture, and we discuss several related problems. Namely, we show that the interpretability join of two idempotent varieties that are not congruence modular is not congruence modular either, and the analogue for idempotent va- rieties with a cube term. In the second part, we give a relational description of higher commutator operators, which were introduced by Bulatov, in varieties with a Mal'cev term. Furthermore, we use this result to prove that for every algebra with a Mal'cev term there exists a largest clone containing the Mal'cev operation and having the same congruence lattice and the same higher commu- tator operators as the original algebra, and to describe explicit (though infinite) set of identities describing supernilpotence..
CSP over oriented trees
No full textIn this thesis we present an oriented tree with only 26 vertices, whose CSP is NP-complete. This serves as a counterexample for a conjecture that any oriented tree with this property has at least 39 vertices. The work itself is divided into three chapters. In the first one, basic definitions and tools of this topic are introduced. Then, tractability of trees of special shapes is shown. Finally, NP-completeness of a certain oriented tree is proven.
Primality testing using elliptic curves
No full textIn the present work we study primality tests. A primality test is an algorithm for determining whether an input number is prime. In the first part of this work we recapitulate the basic definitions and facts about number theory and study Pocklington's algorithm, that based on the group (Z/nZ)∗ . Then we study Generalized Pocklington's primality test and Pépin's primality test for Fermat numbers. In the second part of this work we represent the basic definitions and facts about elliptic curves. Then we study Goldwasser-Killian primality test, that based on elliptic curves. One part of this work is experementation with Goldwasser-Killian primality test.
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