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Study of Some Single Crystals of the CuxHg1–xCr2Se4 System Single crystals of the CuxHg1–xCr2Se4 for 0 ≤ x ≤ 0.077 were prepared by the chemical transport method. The crystals were analyzed and investigated by X-rays. Some electric and magnetic properties of the single crystals were determined and the results obtained are discussed. 相似文献
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Let K be the field of real or complex numbers. Let (X K2n,) be a symplectic vector space and take 0 < k < n,N =. Let L1,...,LN X be 2k-dimensionallinear subspaces which are in a sufficiently general position.It is shown that if F : X X is a linear automorphism whichpreserves the form k on all subspaces L1,...,LN, then F is ank-symplectomorphism (that is, F* = k, where ). In particular, if K = R and k is odd then F mustbe a symplectomorphism. The unitary version of this theoremis proved as well. It is also observed that the set Al,2r ofall l-dimensional linear subspaces on which the form has rank 2r is linear in the Grassmannian G(l,2n), that is, there isa linear subspace L such that Al,2r = L G(l, 2n). In particular,the set Al,2r can be computed effectively. Finally, the notionof symplectic volume is introduced and it is proved that itis another strong invariant. 相似文献
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Wlodzimierz Jelonek 《Proceedings of the American Mathematical Society》2001,129(1):247-256
The aim of this paper is to give a characterization of 3-K-contact and quasi 3-K-contact manifolds.
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Zbigniew Jelonek 《Proceedings of the American Mathematical Society》2003,131(5):1361-1367
Let be a polynomial of degree . Assume that the set there is a sequence s.t. and is finite. We prove that the set of generalized critical values of (hence in particular the set of bifurcation points of ) has at most points. Moreover, We also compute the set effectively.
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Zbigniew Jelonek 《Proceedings of the American Mathematical Society》2005,133(9):2539-2542
Let be a smooth complete three-dimensional algebraic variety (defined over an algebraically closed field ). We show that is projective if it contains a divisor which is positive on the cone of effective curves.
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Let be the field of real or complex numbers. Let (X 2n, )be a symplectic affine space. We study the group of polynomialsymplectomorphisms of X. We show that for an arbitrary k thegroup of polynomial symplectomorphisms acts k-transitively onX. Moreover, if 2 l 2n – 2 then elements of this groupcan be characterized by polynomial automorphisms which preservethe symplectic type of all algebraic l-dimensional subvarietiesof X. 相似文献
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Zbigniew Jelonek 《manuscripta mathematica》2003,110(2):145-157
Let be a polynomial dominant mapping and let deg f
i
≤d. We prove that the set K(f) of generalized critical values of f is contained in the algebraic hypersurface of degree at most D=(d+s(m−1)(d−1))
n
, where . This implies in particular that the set B(f) of bifurcations points of f is contained in the hypersurface of degree at most D=(d+s(m−1)(d−1))
n
. We give also an algorithm to compute the set K(f) effectively.
Received: 11 June 2001 / Revised version: 1 July 2002 Published online: 24 January 2003
The author is partially supported by the KBN grant 2 PO3A 017 22.
Mathematics Subject Classification (2000): 14D06, 14Q20, 51N10, 51N20, 15A04 相似文献
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