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591.
We introduce some alternative definitions of the concept of computable automorphism of a set of natural numbers. We study their relationships and investigate whether some classes of sets having isomorphic groups of automorphisms coincide with other classes of sets usual in computability. Finally, we show that the classification of sets by these groups of automorphisms is nontrivial. 相似文献
592.
We consider one‐factorizations of K2n possessing an automorphism group acting regularly (sharply transitively) on vertices. We present some upper bounds on the number of one‐factors which are fixed by the group; further information is obtained when equality holds in these bounds. The case where the group is dihedral is studied in some detail, with some non‐existence statements in case the number of fixed one‐factors is as large as possible. Constructions both for dihedral groups and for some classes of abelian groups are given. © 2002 John Wiley & Sons, Inc. J Combin Designs 10: 1–16, 2002 相似文献
593.
A Mumford curve of genus g=5,6,7 or 8 over a non-Archimedean field ofcharacteristic p (such that if p=0, the residue field characteristic exceeds 5) has at most 12(g–1) automorphisms. In this paper, all curves that attain this bound and their automorphism groups (called of Lamé type) are explicitly determined. 相似文献
594.
Alice Devillers 《组合设计杂志》2003,11(3):153-161
A Steiner system (or t — (v, k, 1) design) S is said to be homogeneous if, whenever the substructures induced on two finite subsets S1 and S2 of S are isomorphic, there is at least one automorphism of S mapping S1 onto S2, and is said to be ultrahomogeneous if each isomorphism between the substructures induced on two finite subsets of S can be extended to an automorphism of S. We give a complete classification of all homogeneous and ultrahomogeneous Steiner systems. © 2003 Wiley Periodicals, Inc. J Combin Designs 11: 153–161, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jcd.10034 相似文献
595.
596.
In this paper, we investigate Hadamard matrices of order 2(p + 1) with an automorphism of odd prime order p. In particular, the classification of such Hadamard matrices for the cases p = 19 and 23 is given. Self‐dual codes related to such Hadamard matrices are also investigated. © 2003 Wiley Periodicals, Inc. J Combin Designs 11: 367–380, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jcd.10052 相似文献
597.
We prove that the filter of computability potentials of semiprimal algebras is preserved under an arbitrary automorphism of the computability potential scale. 相似文献
598.
确定了超特殊Z-群的自同构群.设G是超特殊Z-群,即G={(1 α_1 α_2···α_n α_(n+1) 0 1 0···0 α_(n+2) ···0 0 0 ··· 0 α_2n 0 0 0··· 1 α_(2n+1) 0 0 0···1 α_(2n+1) 0 0 0···0 1)|α_j∈Z,j=1,2,3,...,2n+1}Aut_cG是AutG中平凡作用在ζG上的自同构形成的正规子群,则AutG=Aut_cG×Z_2,且1→Z···Z}2N→Aut_cG→Sp(2n,Z)→1是正合列. 相似文献
599.
A natural topic of algebraic graph theory is the study of vertex transitive graphs. In the present article, we investigate locally 3‐transitive graphs of girth 4. Taking our former results on locally symmetric graphs of girth 4 as a starting point, we show what properties are retained if we weaken the requirement of local symmetry to local 3‐transitivity. 相似文献
600.