منابع مشابه
IDEMPOTENT n-PERMUTABLE VARIETIES
One of the important classes of varieties identified in tame congruence theory is the class of varieties which are n-permutable for some n. In this paper we prove two results: (1) For every n > 1 there is a polynomial-time algorithm which, given a finite idempotent algebra A in a finite language, determines whether the variety generated by A is n-permutable; (2) A variety is n-permutable for so...
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We discuss two generalizations of Lie groupoids. One consists of Lie n-groupoids defined as simplicial manifolds with trivial πk≥n+1. The other consists of stacky Lie groupoids G ⇒ M with G a differentiable stack. We build a 1–1 correspondence between Lie 2-groupoids and stacky Lie groupoids up to a certain Morita equivalence. We prove this in a general set-up so that the statement is valid in ...
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Brevity is the soul of wit. William Shakespeare A cyclically permutable code is a set of codewords having the property that no codeword is a cyclic shift of another codeword. We study the problem of constructing cyclically permutable codes of large size and low correlation. Cyclically permutable codes are used in code-division multiple-access systems realized by e.g. direct-sequence modulation ...
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We show that if f and g are transcendental entire functions such that f(g) = g(f), then f satisfies an algebraic differential equation if and only if g does.
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We prove that every distributive algebraic lattice with at most א1 compact elements is isomorphic to the normal subgroup lattice of some group and to the submodule lattice of some right module. The א1 bound is optimal, as we find a distributive algebraic lattice D with א2 compact elements that is not isomorphic to the congruence lattice of any algebra with almost permutable congruences (hence n...
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ژورنال
عنوان ژورنال: Czechoslovak Mathematical Journal
سال: 1984
ISSN: 0011-4642,1572-9141
DOI: 10.21136/cmj.1984.101965