共查询到20条相似文献,搜索用时 15 毫秒
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In this paper we study common fixed points for the self and non-self (g, f) type maps in cone metric spaces. Our main results are related to the cases when g is f quasi contraction in a sense of Das and Naik, and the cone need not be normal. These results generalize several well known comparable results in the literature. 相似文献
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There are several notions of largeness in a semigroup S that originated in topological dynamics. Among these are thick, central, syndetic and piecewise syndetic. Of these, central sets are especially interesting because they are partition regular and are guaranteed to contain substantial combinatorial structure. It is known that in (N,+) any central set may be partitioned into infinitely many pairwise disjoint central sets. We extend this result to a large class of semigroups (including (N,+)) by showing that if S is a semigroup in this class which has cardinality κ then any central set can be partitioned into κ many pairwise disjoint central sets. We also show that for this same class of semigroups, if there exists a collection of μ almost disjoint subsets of any member S, then any central subset of S contains a collection of μ almost disjoint central sets. The same statement applies if “central” is replaced by “thick”; and in the case that the semigroup is left cancellative, “central” may be replaced by “piecewise syndetic”. The situation with respect to syndetic sets is much more restrictive. For example, there does not exist an uncountable collection of almost disjoint syndetic subsets of N. We investigate the extent to which syndetic sets can be split into disjoint syndetic sets. 相似文献
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Homotopies for computation of fixed points 总被引:2,自引:0,他引:2
B. Curtis Eaves 《Mathematical Programming》1972,3(1):1-22
Given a point to set mapf on a simplex with certain conditions, an algorithm for computing fixed points is described. The algorithm operates by following the fixed point as an initially affine function is deformed towardsf.
This research was supported in part by Army Research Office Durham Contract DAHC-04-67-C-0028 and in part by NSF Grant GK-5695. 相似文献
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Pierre Dèbes 《manuscripta mathematica》1996,89(1):107-137
A classical tool for studying Hilbert's irreducibility theorem is Siegel's finiteness theorem forS-integral points on algebraic curves. We present a different approach based ons-integral points rather thanS-integral points. Given an integers>0, an elementt of a fieldK is said to bes-integral if the set of placesv ∈M
K for which |t|v > l is of cardinality ≤s (instead of contained inS for “S-integral”). We prove a general diophantine result fors-integral points (Th.1.4). This result, unlike Siegel's theorem, is effective and is valid more generally for fields with
the product formula. The main application to Hilbert's irreducibility theorem is a general criterion for a given Hilbert subset
to contain values of given rational functions (Th.2.1). This criterion gives rise to very concrete applications: several examples
are given (§2.5). Taking advantage of the effectiveness of our method, we can also produce elements of a given Hilbert subset
of a number field with explicitely bounded height (Cor.3.7). Other applications, including the case thatK is of characteristicp>0, will be given in forthcoming papers ([8], [9]). 相似文献
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Let be the number of conjugacy classes of elements in SL(2, ) with trace t, and let be the number of equivalence classes of binary quadratic forms with discriminant n. Then for t≠±2, . For all real θ > 0 there is a T(θ) such that whenever |t|>T(θ), . There is a c>0 such that for those t such that t2?4 is squarefree, . 相似文献
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Jay R. Goldman 《Aequationes Mathematicae》1975,13(1-2):155-156
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In this paper, we will show some connections between fixed point and coupled fixed point problems in Banach and metric spaces. 相似文献
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Approximate fixed points for discontinuous set-valued mappings 总被引:1,自引:0,他引:1
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The purpose of this paper is to prove a common fixed point theorem, from the class of compatible continuous maps to a larger
class of maps having weakly compatible maps without appeal to continuity, which generalizes the results of Jungck [3], Fisher
[1], Kang and Kim [8], Jachymski [2], and Rhoades [9]. 相似文献