منابع مشابه
Minimal Covers of Formal Languages
Let L1; L2 be languages. If L1 L2, then we say that L2 covers L1. Let C;D be classes of languages over . We call a cover L2 2 C of L1 a C-minimal cover with respect to D if, for all L0 2 C, L1 L0 L2 implies L2 L0 2 D. We examine in detail the particular cases of minimal regular covers and minimal context-free covers, both with respect to nite languages. The closure properties of the class of la...
متن کاملMinimal Covers and Arithmetical Sets1
If a and b are degrees of unsolvability, a is called a minimal cover of b if b<a and no degree c satisfies b<c<a. The degree a is called a minimal cover if it is a minimal cover of some degree b. We prove by a very simple argument that 0" is not a minimal cover for any n. From this result and the axiom of Borel determinateness (BD) we show that the degrees of arithmetical sets (with their usual...
متن کاملMINIMAL COVERS AND HYPERDEGREESf 1 )
Every hyperdegree at or above that of Kleene's O is the hyperjump and the supremum of two minimal hyperdegrees (Theorem 3.1). There is a nonempty ~ZX class of number-theoretic predicates each of which has minimal hyperdegree (Theorem 4.7). If V = L or a generic extension of L, then there are arbitrarily large hyperdegrees which are not minimal over any hyperdegree (Theorems 5.1, 5.2). If <?# ex...
متن کاملMinimal vertex covers on finite-connectivity random graphs: a hard-sphere lattice-gas picture.
The minimal vertex-cover (or maximal independent-set) problem is studied on random graphs of finite connectivity. Analytical results are obtained by a mapping to a lattice gas of hard spheres of (chemical) radius 1, and they are found to be in excellent agreement with numerical simulations. We give a detailed description of the replica-symmetric phase, including the size and entropy of the mini...
متن کاملFan-KKM Theorem in Minimal Vector Spaces and its Applications
In this paper, after reviewing some results in minimal space, some new results in this setting are given. We prove a generalized form of the Fan-KKM typetheorem in minimal vector spaces. As some applications, the open type of matching theorem and generalized form of the classical KKM theorem in minimal vector spaces are given.
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ژورنال
عنوان ژورنال: Bulletin of the Australian Mathematical Society
سال: 1971
ISSN: 0004-9727,1755-1633
DOI: 10.1017/s0004972700046232