On commutativity and approximation
نویسندگان
چکیده
منابع مشابه
fragmentability and approximation
in chapter 1, charactrizations of fragmentability, which are obtained by namioka (37), ribarska (45) and kenderov-moors (32), are given. also the connection between fragmentability and its variants and other topics in banach spaces such as analytic space, the radone-nikodym property, differentiability of convex functions, kadec renorming are discussed. in chapter 2, we use game characterization...
15 صفحه اولOn strong commutativity-preserving maps
Let R be a ring with center Z(R). We write the commutator [x, y] = xy− yx, (x, y ∈ R). The following commutator identities hold: [xy,z] = x[y,z] + [x,z]y; [x, yz] = y[x,z] + [x, y]z for all x, y,z ∈ R. We recall that R is prime if aRb = (0) implies that a= 0 or b = 0; it is semiprime if aRa = (0) implies that a = 0. A prime ring is clearly a semiprime ring. A mapping f : R→ R is called centrali...
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Let G be a group and let k > 2 be an integer, such that (A: — 3)(A: — 1) < |G|/15 if G is finite. Suppose that the condition \A\ < k(k+l)/2 + (k-'i)/2 is satisfied by every it-element subset A c G. Then G is abelian. The proof uses the structure of quasi-invariant sets.
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ژورنال
عنوان ژورنال: Theoretical Computer Science
سال: 1983
ISSN: 0304-3975
DOI: 10.1016/0304-3975(83)90068-3