Báo cáo toán học: "The toric ideal of a matroid of rank 3 is generated by quadrics" pps

... matroid M in C, I M is generated by quadratic binomials corresponding to symmetric exchanges. The deletion of a matroid of rank 3 is of rank at most 3. Adding parallel elements to a matroid of ... We may assume that cfi is a flat of rank 1 and cefikl is a flat of rank 2 on cefghijkl (the left-hand side of Figure 10). Note that the flat of rank...

Ngày tải lên: 08/08/2014, 12:22

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Ngày tải lên: 05/08/2014, 10:20

... (2 .3) Proof. The proof is a simple analogue of the ODE case given in [2] (the idea is to use boundedness of A, B, A −1 1 ,P  and a property of the matrix norm).  Note that formula (2 .3) can ... Introduction Differential algebraic equations (DAEs) have been developed as a highly topical subject of applied mathematics. The research on this topic has been carried out by...

Ngày tải lên: 06/08/2014, 05:20

... Combina- torica,toappear. [14] P. Keevash and B. Sudakov, On a hypergraph Tur´an problem of Frankl, Combina- torica,toappear. [15] D. Mubayi, On hypergraphs with every four points spanning at most ... a 3- uniform hypergraph F that does not contain a forest with 3 edges. We can assume that F is not 3- partite (Erd˝os [4] showed that this implies π(F)=0)so F has at least 3 edge...

Ngày tải lên: 07/08/2014, 08:22

... Then we may assume that e w ¯ J may be written as a linear combination of column standard polytabloids by Lemma 3. 1. Thus, because of Remark 3. 4, we may always take w ¯ J to have standard columns. ... be a pair of partitions of n such that λ is a partition of |λ| and µ is a partition of |µ|, and |λ| + |µ| = n. Many results about representations of the hyperocta...

Ngày tải lên: 07/08/2014, 21:20

... another array by flipping about the central line of the array. We shall enumerate the faces of CP(n, d) that are invariant under C ′ -action. We treat the cases of odd d and even d separately. the ... are g(9, 7, 4) = 125 faces of dimension 3 in CP(9, 7), whose arrays contain 4 stars and at most 3 odd inner blocks. By Theorem 4.2(ii), the number of 3- faces that are C ′ -inv...

Ngày tải lên: 08/08/2014, 12:22

... linear Hamiltonian sys- tems. J. Diff. Eqs. 252, 35 8 38 1 (2012) [10] Wang, X: Stability criteria for linear periodic Hamiltonian systems. J. Math. Anal. Appl. 36 7, 32 9 33 6 (2010) [11] Wang, X: Lyapunov ... (zhqm20082008@sina.com) Xiaofei He (hexiaofei525@sina.com) ISSN 1029-242X Article type Research Submission date 19 October 2011 Acceptance date 12 January 2012 Publication date 12 Ja...

Ngày tải lên: 20/06/2014, 21:20

... ≥ max {a 1 , ,a r }. Folkman [3] proved that there exists a graph G such that G → (a 1 , ,a r )andcl(G)=max {a 1 , ,a r }. Therefore F (a 1 , ,a r ; q) exists if and only if q>max {a 1 , ,a r }. ... easily handle the case r ≥ 3. It is clear that G → (a 1 , ,a r ) ⇔ G → (a ϕ(1) , ,a ϕ(r) ) for any permutation ϕ ∈ S r . That is why we may assume that a 1 ≤ ≤ a r ≤ p....

Ngày tải lên: 07/08/2014, 13:21

... Accepted: Jan 4, 2010; Published: Jan 14, 2010 Mathematics Subject Classifications: 0 5A1 9, 11B68 Abstract In this paper we establish some symmetric identities on a sequence of polynomials in an ... xt)dt. (3. 10) the electronic journal of combinatorics 17 (2010), #N7 6 Inspired by the above work, in this paper we generalize the above authors’ results in an elementary way, and obtain...

Ngày tải lên: 08/08/2014, 01:20

... 31 4, 135 24, 235 14, 32 514, 4251 3, 524 13, 145 23, 245 13, 34 512, 435 12, 534 12}, D I = {21 435 , 21 534 , 31 425, 31 524, 32 415, 32 514, 4 132 5, 415 23, 4 231 5, 425 13, 435 12, 51 32 4, 514 23, 5 231 4, 524 13, 534 1 ... permutat io n σ = 524 13 is I = (1, 2, 2) and D I = {1 234 5, 2 134 5, 31 245, 41 235 , 51 234 , 12 435 , 21 435 , 31 425, 4 132 5, 5 132 4, 12 534...

Ngày tải lên: 08/08/2014, 12:22