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981.
Anthony Bonato 《Mathematical Logic Quarterly》2001,47(2):147-160
We prove that each ∀1 free amalgamation class K over a finite relational language L admits a countable generic structure M isometrically embedding all countable structuresin K relative to a fixed metric. We expand L by infinitely many binary predicates expressingdistance, and prove that the resulting expansion of K has a model companion axiomatizedby the first‐order theory of M. The model companion is non‐finitely axiomatizable, evenover a strong form of the axiom scheme of infinity. 相似文献
982.
Barthelmann Volker Novak Erich Ritter Klaus 《Advances in Computational Mathematics》2000,12(4):273-288
We study polynomial interpolation on a d-dimensional cube, where d is large. We suggest to use the least solution at sparse grids with the extrema of the Chebyshev polynomials. The polynomial exactness of this method is almost optimal. Our error bounds show that the method is universal, i.e., almost optimal for many different function spaces. We report on numerical experiments for d = 10 using up to 652 065 interpolation points. This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
983.
Karlheinz Knapp 《K-Theory》1999,18(2):137-159
We study Anderson duality for connective K-theory l and Im(J)-theory A, the latter being the p-localization of Quillen's algebraic K-theory of a suitably chosen finite field. The interplay between Anderson duality and Postnikov decomposition results in a construction of two families of natural transformations from ordinary cohomology theory to l* and A*-theory, which are related to the Chern character. These operations are then used to study l*(l) and A*(A), the cohomology operations of connective K-theory and Im(J)-theory. 相似文献
984.
Suppose G is a definably connected, definable group in an o‐minimal expansion of an ordered group. We show that the o‐minimal universal covering homomorphism : → G is a locally definable covering homomorphism and π1(G) is isomorphic to the o‐minimal fundamental group π (G) of G defined using locally definable covering homomorphisms. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
985.
We consider a finite dimensional representation of the dihedral group D2p over a field of characteristic two where p is an odd integer and study the corresponding Hilbert ideal IH. We show that IH has a universal Gröbner basis consisting of invariants and monomials only. We provide sharp bounds for the degree of an element in this basis and in a minimal generating set for IH. We also compute the top degree of coinvariants when p is prime. 相似文献
986.
M.L. Gerver 《Applicable analysis》2013,92(1-4):253-270
Travel-time inversion is a fundamental problem of mathematical geophysics: explosions and earthquakes occur on (or close to) the surface of the Earth, instruments record signals from them, and the problem is to find the velocity of elastic waves in the interior of the Earth from the times taken by the signals travelling from the sources to the receivers. In the classical formulation of the problem the wave velocity is assumed to depend only on the depth. This classical inverse problem has just recently seemed to be completely exhausted. However, it has turned out not to be the case. This paper relates the newest results in the problem, presents new key notions emerged in the last years research and explains-using duality principle-why discrete measures (or, in geophysical terms, waveguides with a finite number of layers) are so significant for describing ambiguity in travel-time inversion. 相似文献
987.
Michael Marz 《Applied Categorical Structures》1999,7(1-2):147-157
We present an algebraic framework that provides a general notion of recursive types. We characterize those type systems that guarantee the subject reduction property. Finally, we prove a strong normalization and a principle typing result. 相似文献
988.
989.
Pulling back the weight system associated with the exceptional Lie algebra by a modification of the universal Vassiliev-Kontsevich invariant yields a link invariant; extending it to 3-nets, we derive a recursive algorithm for its evaluation. Received: April 16, 1998 相似文献
990.
R. Sh. Omanadze 《Mathematical Notes》1999,66(2):174-180
The existence of a recursively enumerable (RE)T-degreea that does not contain an RE semirecursive setA ∈a with theQ-universal splitting property is proved. Each nonrecursive RE contiguous degree contains an RE setA with the universalT-Q-reduction property, butA is notT-Q-maximal. Each nonrecursive REW-degree contains an RE setA with the universalW-sQ-reduction property, butA is notW-sQ-maximal. Each creative set is partially semimaximal. Translated fromMatematicheskie Zametki, Vol. 66, No. 2, pp. 220–230, August, 1999. 相似文献