I-图的可扩性

如果连通图I中任意n条点不交的边都包含在一个完美匹配中,就称I是n-可扩的.证明了真I图I(n,j,k)是1-可扩的;当n≠3j或者3k时,真I-图是2-可扩的.     

Isomorphism on Hypergroups

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Isomorphism is equality

The setting of this work is dependent type theory extended with the univalence axiom. We prove that, for a large class of algebraic structures, isomorphic instances of a structure are equal—in fact, isomorphism is in bijective correspondence with equality. The class of structures includes monoids whose underlying types are “sets”, and also posets where the underlying types are sets and the ordering relations are pointwise “propositional”. For monoids on sets equality coincides with the usual notion of isomorphism from universal algebra, and for posets of the kind mentioned above equality coincides with order isomorphism.     

Faster Subtree Isomorphism

We study the subtree isomorphism problem: Given trees H and G, find a subtree of G which is isomorphic to H or decide that there is no such subtree. We give an O((k^1.5/log k)n)-time algorithm for this problem, where k and n are the number of vertices in H and G, respectively. This improves over the O(k^1.5n) algorithms of Chung and Matula. We also give a randomized (Las Vegas) O(k^1.376n)-time algorithm for the decision problem.     

Isomorphism in Wavelets

Journal of Fourier Analysis and Applications - Two scaling functions $$\varphi _A$$ and $$\varphi _B$$ for Parseval frame wavelets are algebraically isomorphic, $$\varphi _A \simeq \varphi _B$$, if...     

Isomorphism of random walks

We show that any two aperiodic, recurrent random walks on the integers whose jump distributions have finite seventh moment, are isomorphic as infinite measure preserving transformations. The method of proof involved uses a notion of equivalence of renewal sequences, and the “relative” isomorphism of Bernoulli shifts respecting a common state lumping with the same conditional entropy. We also prove an analogous result for random walks on the two dimensional integer lattice.     

Isomorphism of spiral polygons

We call two polygonsisomorphic if there is a one-to-one mapping between theirpoints (not vertices) that preserves visibility. In this paper we establish necessary and sufficient conditions for two spiral polygons to be isomorphic, and give anO(n ² ) algorithm to detect such isomorphism. We also show that the continuous graph of visibility on the points of a spiral polygon is an (uncountably infinite) interval graph, and that no other polygons have this property. This research was supported by the Natural Sciences and Engineering Research Council of Canada under Research Grant Number OGP0046218 and a Post-Graduate Scholarship.     

格序向量空间的同构

研究了 l-向量空间的凸同余关系、同构关系 ,将 l-群的同构定理推广到 l-向量空间 .     

Isomorphism Classes of A-Hypergeometric Systems

Given a finite set A of integral vectors and a parameter vector, Gel'fand, Kapranov, and Zelevinskii defined a system of differential equations, called an A-hypergeometric (or a GKZ hypergeometric) system. Classifying the parameters according to the D-isomorphism classes of their corresponding A-hypergeometric systems is one of the most fundamental problems in the theory. In this paper we give a combinatorial answer for the problem under the assumption that the finite set A lies in a hyperplane off the origin, and illustrate it in two particularly simple cases: the normal case and the monomial curve case.     

Isomorphism of generalized matrix rings

An isomorphism problem is considered for generalized matrix rings with values in a given ring R. An exhaustive answer is given for the case of a commutative domain R and a commutative local ring R.     

Isomorphism types of Aronszajn trees

We study the isomorphism types of Aronszajn trees of height ω₁ and give diverse results on this question (mainly consistency results). The second author would like to thank the United States-Israel Binational Science Foundation for partially supporting this research by a grant.     

Isomorphism of one-place functors Ext

Let be an associative ring with identity. One considers the category of left (unitary) -modules m and also the contravariant and the covariant functors Ext ¹ ( ,A) and Ext ¹ (A, ): M_z M. One proves the following results: (1) If the homomorphism of -modules A B induces an isomorphism Ext ¹ ( ,A)Ext ¹ ( ,B), then there exist injective -modules J₁ and J₂ such that AJ₁BJ₂. (2) Every functorial morphism Ext ¹ ( ,A)Ext ¹ ( ,B) induces a certain homomorphism of -modules AB. One also obtains a dual result.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 112, pp. 71–74, 1981.