共查询到20条相似文献,搜索用时 31 毫秒
1.
Thomas Britz Trygve Johnsen Dillon Mayhew Keisuke Shiromoto 《Designs, Codes and Cryptography》2012,62(3):331-341
We present several fundamental duality theorems for matroids and more general combinatorial structures. As a special case,
these results show that the maximal cardinalities of fixed-ranked sets of a matroid determine the corresponding maximal cardinalities
of the dual matroid. Our main results are applied to perfect matroid designs, graphs, transversals, and linear codes over
division rings, in each case yielding a duality theorem for the respective class of objects. 相似文献
2.
Saharon Shelah 《Archive for Mathematical Logic》2002,41(5):401-441
We construct Boolean algebras with prescribed behaviour concerning depth for the free product of two Boolean algebras over
a third, in ZFC using pcf; assuming squares we get results on ultraproducts. We also deal with the family of cardinalities
and topological density of homomorphic images of Boolean algebras (you can translate it to topology - on the cardinalities
of closed subspaces); and lastly we deal with inequalities between cardinal invariants, mainly .
Received: 9 September 1998 / Published online: 7 May 2002 相似文献
3.
Semigroup Forum - We completely determine all varieties of monoids on whose free objects all fully invariant congruences or all fully invariant congruences contained in the least semilattice... 相似文献
4.
We prove that an equational class of Hilbert algebras cannot be defined by a single equation. In particular Hilbert algebras
and implication algebras are not one-based. Also, we use a seminal theorem of Alfred Tarski in equational logic to characterize
the set of cardinalities of all finite irredundant bases of the varieties of Hilbert algebras, implication algebras and commutative
BCK algebras: all these varieties can be defined by independent bases of n elements, for each n > 1.
相似文献
5.
Igor Dolinka 《Journal of Pure and Applied Algebra》2009,213(10):1979-1990
We show that a finite completely regular semigroup has a sub-log-exponential free spectrum if and only if it is locally orthodox and has nilpotent subgroups. As a corollary, it follows that the Seif Conjecture holds true for completely regular monoids. In the process, we derive solutions of word problems of free objects in a sequence of varieties of locally orthodox completely regular semigroups from solutions of word problems in relatively free bands. 相似文献
6.
We classify and explicitly describe maximal antipodal sets of some compact classical symmetric spaces and those of their quotient spaces by making use of suitable embeddings of these symmetric spaces into compact classical Lie groups. We give the cardinalities of maximal antipodal sets and we determine the maximum of the cardinalities and maximal antipodal sets whose cardinalities attain the maximum. 相似文献
7.
Linear and quadratic programming approaches for the general graph partitioning problem 总被引:1,自引:0,他引:1
The graph partitioning problem is to partition the vertex set of a graph into a number of nonempty subsets so that the total
weight of edges connecting distinct subsets is minimized. Previous research requires the input of cardinalities of subsets
or the number of subsets for equipartition. In this paper, the problem is formulated as a zero-one quadratic programming problem
without the input of cardinalities. We also present three equivalent zero-one linear integer programming reformulations. Because
of its importance in data biclustering, the bipartite graph partitioning is also studied. Several new methods to determine
the number of subsets and the cardinalities are presented for practical applications. In addition, hierarchy partitioning
and partitioning of bipartite graphs without reordering one vertex set, are studied. 相似文献
8.
Siberian Mathematical Journal - We study the topological properties and cardinalities of the sets of strict local minima of functions on f-quasimetric and topological spaces. 相似文献
9.
Analyzing diagrams forming generative classes, we describe definable sets and their links in generic structures as well as cardinality bounds for these definable sets, finite or infinite. Introducing basic characteristics for definable sets in generic structures, we compare them each others and with cardinalities of these sets.We introduce calculi for (type-)definable sets allowing to compare their cardinalities. In terms of these calculi, Trichotomy Theorem for possibilities comparing cardinalities of definable sets is proved. Using these calculi, we characterize the possibility to construct a generic structure of a given generative class. 相似文献
10.
K. Zh. Kudaĭbergenov 《Siberian Advances in Mathematics》2011,21(4):282-291
We refute the strong version of Shelah’s conjecture about models of large cardinalities, the independence property, and indiscernible
sequences. We find necessary and sufficient conditions for a theory to lack the independence property and present applications
of these conditions. 相似文献
11.
12.
Zhiwei Yun 《Selecta Mathematica, New Series》2009,14(2):299-320
We describe several general methods for calculating weights of mixed tilting sheaves. We introduce a notion called “non-cancellation
property” which implies a strong uniqueness of mixed tilting sheaves and enables one to calculate their weights effectively.
When we have a certain Radon transform, we prove a geometric analogue of Ringel duality which sends tilting objects to projective
objects. We apply these methods to (partial) flag varieties and affine (partial) flag varieties and show that the weight polynomials
of mixed tilting sheaves on flag and affine flag varieties are essentially given by Kazhdan-Lusztig polynomials. This verifies
a mixed geometric analogue of a conjecture by W. Soergel in [10].
相似文献
13.
C. A. Morales 《数学学报(英文版)》2015,31(9):1501-1507
We prove that the existence of positively expansive measures for continuous maps on compact metric spaces implies the existence of e 0 and a sequence of(m, e)-separated sets whose cardinalities go to infinite as m →∞. We then prove that maps exhibiting such a constant e and the positively expansive maps share some properties. 相似文献
14.
Yi Zhang 《Archive for Mathematical Logic》2000,39(1):41-52
We discuss the cardinalities of maximal cofinitary groups under the assumption of . We also discuss various open questions in this area.
Received: 24 July 1997 相似文献
15.
Norman R. Reilly 《Semigroup Forum》2013,86(1):162-182
In a previous paper, the author showed how to associate a completely 0-simple semigroup with a connected bipartite graph containing labelled edges. In the main theorem, it is shown how these fundamental semigroups can be used to describe the regular principal factors of the free objects in certain Rees-Sushkevich varieties, namely, the varieties of semigroups that are generated by all completely 0-simple semigroups over groups in a variety of finite exponent. This approach is then used to solve the word problem for each of these varieties for which the corresponding group variety has solvable word problem. 相似文献
16.
In 2006, P. J. Cameron and J. Ne?et?il introduced the following variant of homogeneity: we say that a structure is homomorphism-homogeneous if every homomorphism between finitely generated substructures of the structure extends to an endomorphism of the structure. In several recent papers homomorphism-homogeneous objects in some well-known classes of algebras have been investigated (e.g. lattices and semilattices), while finite homomorphism-homogeneous groups were described in 1979 under the name of finite quasiinjective groups. In this paper we characterize homomorphism-homogenous monounary algebras of arbitrary cardinalities. 相似文献
17.
Csaba Sz��nt�� 《Mathematische Zeitschrift》2011,269(3-4):833-846
We deduce using the Ringel?CHall algebra approach explicit formulas for the cardinalities of some Grassmannians over a finite field associated to the Kronecker quiver. We realize in this way a quantification of the formulas obtained by Caldero and Zelevinsky for the Euler characteristics of these Grassmannians. Finally we present a recursive algorithm for computing the cardinality of every Kronecker quiver Grassmannian over a finite field. 相似文献
18.
Beka Ergemlidze 《Discrete Mathematics》2021,344(4):112262
In this paper, we consider maximum possible value for the sum of cardinalities of hyperedges of a hypergraph without a Berge 4-cycle. We significantly improve the previous upper bound provided by Gerbner and Palmer. Furthermore, we provide a construction that slightly improves the previous lower bound. 相似文献
19.
Qunhua Liu 《代数通讯》2013,41(12):5080-5093
We explicitly describe all spherical objects, as well as tilting objects, of the multiplicity free Brauer tree algebra with two edges. 相似文献
20.
《Discrete Mathematics》2001,221(1-3):387-393
A family of sets has the equal union property if and only if there exist two nonempty disjoint subfamilies having the same union. We prove that any n nonempty subsets of an n-element set have the equal union property if the sum of their cardinalities exceeds n(n+1)/2. This bound is tight. Among families in which the sum of the cardinalities equals n(n+1)/2, we characterize those having the equal union property. 相似文献