제목  OneDay Meeting in Combinatorics  

작성자  관리자  등록일  20170921  조회수  305 
Jeffrey Remmel (Univ. of California, San Diego, USA) Title: Stieltjes moment sequences of polynomials Date: 10:00  11:00, Sep. 13, 2017 (AORC Seminar Room)
Abstract:
A sequence is Stieltjes moment sequence if it has the form for is a nonnegative measure on. It is known that is Stieltjes moment sequence if and only if the matrix is totally positive, i.e., all its minors are nonnegative. We define a sequence of polynomials in to be Stieltjes moment sequence of polynomials if the matrix is totally positive, i.e., all its minors are polynomials in with nonnegative coefficients. We shall show that one can construct a large number of examples Stieltjes moment
Sergey Kitaev (Univ. of Strathclyde, UK) Title: An introduction to the theory of wordrepresentable graphs Date: 11:00  12:00, Sep. 13, 2017 (AORC Seminar Room)
Abstract:
Letters x and y alternate in a word w if after deleting in w all letters but the copies of x and y we either obtain a word xyxy… (of even or odd length) or a word yxyx… (of even or odd length). A graph G=(V,E) is wordrepresentable if and only if there exists a word w over the alphabet V such that letters x and y alternate in w if and only if xy in E.

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다음글  Special Lecture Series of AORC Working Workshop (May 22 ~ June 2, 2017) 