tailieunhanh - Báo cáo toán học: "The non-crossing graph"

Tuyển tập các báo cáo nghiên cứu khoa học về toán học trên tạp chí toán học quốc tế đề tài: The non-crossing graph. | The non-crossing graph Nathan Linial Michael Saks 1 David Statter Ỉ Submitted Apr 7 2005 Accepted Jan 20 2006 Published Jan 25 2006 Mathematics Subject Classifications 05C88 05C89 Abstract Two sets are non-crossing if they are disjoint or one contains the other. The noncrossing graph NCn is the graph whose vertex set is the set of nonempty subsets of n 1 . n with an edge between any two non-crossing sets. Various facts some new and some already known concerning the chromatic number fractional chromatic number independence number clique number and clique cover number of this graph are presented. For the chromatic number of this graph we show n loge n - 0 1 v NCn n log2 n - 1 . 1 Introduction Two sets are non-crossing if they are disjoint or one contains another. The non-crossing graph NCn is the graph whose vertex set is the set of nonempty subsets of n 1 . n and whose edge set is XY X Y are non-crossing . The subgraph of NCn induced on S c n ISI k which we denote here by NCn k is the well known Kneser graph see . 9 4 . For 1 j k n NCn j k denotes the subgraph of NCn induced on S c n j SI k . For W c n NCn W denotes the subgraph induced on the set of subsets whose size lies in W. In this note we collect some facts some new and some previously known about various basic parameters associated with these graphs the chromatic number fractional chromatic number independence number clique number and clique cover number. One reason for studying these graphs is as a first step towards understanding the following abstract simplicial complex. A set X1 . Xk of subsets of n is a shattering School of Computer Science and Engineering Hebrew University Jerusalem 91904 Israel. E-mail nati@. Work supported in part by a grant from the Israel Science Foundation. iDept. of Mathematics Rutgers University New Brunswick NJ. E-mail saks@. Institute of Computer Science Hebrew University Jerusalem 91904 Israel. E-mail stat-ter@. THE ELECTRONIC .

TÀI LIỆU LIÊN QUAN
TỪ KHÓA LIÊN QUAN
crossorigin="anonymous">
Đã phát hiện trình chặn quảng cáo AdBlock
Trang web này phụ thuộc vào doanh thu từ số lần hiển thị quảng cáo để tồn tại. Vui lòng tắt trình chặn quảng cáo của bạn hoặc tạm dừng tính năng chặn quảng cáo cho trang web này.