منابع مشابه
On symmetries of substructures.
This paper accompanies a lecture given at the 2003 CCP4 Study Weekend on experimental phasing. With the audience of the CCP4 Study Weekend in mind, an overview is given of symmetries of substructures and the implications for single isomorphous replacement and single anomalous diffraction phasing procedures, as well as difference Fourier analyses. Pointers are also provided to practical tools fo...
متن کاملCounting substructures II: Hypergraphs
For various k-uniform hypergraphs F , we give tight lower bounds on the number of copies of F in a k-uniform hypergraph with a prescribed number of vertices and edges. These are the first such results for hypergraphs, and extend earlier theorems of various authors who proved that there is one copy of F . A sample result is the following: Füredi-Simonovits [11] and independently KeevashSudakov [...
متن کاملCounting substructures II: triple systems
For various triple systems F , we give tight lower bounds on the number of copies of F in a triple system with a prescribed number of vertices and edges. These are the first such results for hypergraphs, and extend earlier theorems of various authors who proved that there is one copy of F . A sample result is the following: Füredi-Simonovits [10] and independently KeevashSudakov [15] settled an...
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Coloring graphs is an important algorithmic problem in combinatorics with many applications in computer science. In this paper we study coloring tournaments. A chromatic number of a random tournament is of order Ω( n log(n)). The question arises whether the chromatic number can be proven to be smaller for more structured nontrivial classes of tournaments. We analyze the class of tournaments def...
متن کاملCounting substructures III: quadruple systems
For various quadruple systems F , we give asymptotically sharp lower bounds on the number of copies of F in a quadruple system with a prescribed number of vertices and edges. Our results extend those of Füredi, Keevash, Pikhurko, Simonovits and Sudakov who proved under the same conditions that there is one copy of F . Our proofs use the hypergraph removal Lemma and stability results for the cor...
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ژورنال
عنوان ژورنال: Journal of Algebra
سال: 1997
ISSN: 0021-8693
DOI: 10.1006/jabr.1996.6803