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http://hdl.handle.net/10203/23466
2017-11-17T07:38:19ZToroidal graphs containing neither K-5(-) nor 6-cycles are 4-choosable
http://hdl.handle.net/10203/223652
Title: Toroidal graphs containing neither K-5(-) nor 6-cycles are 4-choosable
Authors: Choi, Ilkyoo
Abstract: The choosability (G) of a graph G is the minimum k such that having k colors available at each vertex guarantees a proper coloring. Given a toroidal graph G, it is known that (G)7, and (G)=7 if and only if G contains K-7. Cai etal. (J Graph Theory 65(1) (2010), 1-15) proved that a toroidal graph G without 7-cycles is 6-choosable, and (G)=6 if and only if G contains K-6. They also proved that a toroidal graph G without 6-cycles is 5-choosable, and conjectured that (G)=5 if and only if G contains K-5. We disprove this conjecture by constructing an infinite family of non-4-colorable toroidal graphs with neither K-5 nor cycles of length at least 6; moreover, this family of graphs is embeddable on every surface except the plane and the projective plane. Instead, we prove the following slightly weaker statement suggested by Zhu: toroidal graphs containing neither <mml:msubsup>K5-</mml:msubsup> (a K-5 missing one edge) nor 6-cycles are 4-choosable. This is sharp in the sense that forbidding only one of the two structures does not ensure that the graph is 4-choosable. (C) 2016 Wiley Periodicals, Inc.2017-05-01T00:00:00ZSelective Propylene Carbonate Production form CO2 and Propylene Oxide by a Iron Catalyst
http://hdl.handle.net/10203/223558
Title: Selective Propylene Carbonate Production form CO2 and Propylene Oxide by a Iron Catalyst
Authors: Lee, Dayoung2017-04-21T00:00:00ZThe peer-firm effect on firm's investment decisions
http://hdl.handle.net/10203/223782
Title: The peer-firm effect on firm's investment decisions
Authors: Park, Kwangho; Yang, Insun; Yang, Taeyong
Abstract: This study investigates the effect of peer firms on firm investment strategies. We test the peer group effect hypothesis along differing levels of financially constrained firms as well as differing degrees of industry competition. Using idiosyncratic equity returns as the instrument variable, we use 2-stage least squares regression to identify the influence of peer firms' investment decisions on a firm's own investment policies. Our analyses empirically confirm that there is a peer group effect in making firm investment decisions. More financially constrained firms show greater dependency on peers' investment decisions. Tests of peer sensitivity to the increase in industrial competition, however, displayed a U-shaped quadratic curve, which shows that firms have the lowest peer group effect in medium-competition markets. We claim that imitative behavior in investment is presumably weak in the mid-competition market because firms are yet to be distinguished in this market. (C) 2017 Elsevier Inc. All rights reserved.2017-04-01T00:00:00ZComplete weight enumerators of a class of linear codes
http://hdl.handle.net/10203/223415
Title: Complete weight enumerators of a class of linear codes
Authors: Ahn, Jaehyun; Ka, Dongseok; Li, Chengju
Abstract: Let be the finite field with elements, where p is an odd prime and m is a positive integer. For a positive integer t, let and let be the trace function from onto . In this paper, let we define a p-ary linear code by We shall present the complete weight enumerators of the linear codes and give several classes of linear codes with a few weights. This paper generalizes the results of Yang and Yao (Des Codes Cryptogr, 2016).2017-04-01T00:00:00Z