We prove that, if M is a weakly 4-connected matroid with vertical bar E(M)vertical bar >= 7 and neither M nor M* is isomorphic to the cycle matroid of a ladder, then M has a proper minor M ' such that M' is weakly 4-connected and vertical bar E(M ')vertical bar >= vertical bar E(M)vertical bar - 2 unless M is some 12-element matroid with a special structure. (c) 2007 Elsevier Inc. All rights reserved.
机构:
Univ Western Australia, Sch Math & Stat, Nedlands, WA 6009, AustraliaVictoria Univ Wellington, Sch Math Stat & Operat Res, Wellington 6140, New Zealand
机构:
CNRS, F-91405 Orsay, France
Univ Paris 11, LRI, F-91405 Orsay, France
Lanzhou Univ, Sch Math & Stat, Lanzhou 730000, Peoples R ChinaNankai Univ, Ctr Combinator, Tianjin 300071, Peoples R China
Li, Hao
Tian, Feng
论文数: 0引用数: 0
h-index: 0
机构:
Chinese Acad Sci, Inst Syst Sci, Acad Math & Syst Sci, Beijing 100080, Peoples R ChinaNankai Univ, Ctr Combinator, Tianjin 300071, Peoples R China
Tian, Feng
Xu, Zhi Xia
论文数: 0引用数: 0
h-index: 0
机构:
Nankai Univ, Ctr Combinator, Tianjin 300071, Peoples R China
Nankai Univ, LPMC TJKLC, Tianjin 300071, Peoples R China
Tianjin Polytech Univ, Dept Math, Tianjin 300160, Peoples R ChinaNankai Univ, Ctr Combinator, Tianjin 300071, Peoples R China
机构:
Yokohama Natl Univ, Fac Educ & Human Sci, Hodogaya Ku, Yokohama, Kanagawa 2408501, JapanYokohama Natl Univ, Fac Educ & Human Sci, Hodogaya Ku, Yokohama, Kanagawa 2408501, Japan
Mukae, Raiji
Ozeki, Kenta
论文数: 0引用数: 0
h-index: 0
机构:
Res Org Informat & Syst, Natl Inst Informat, Chiyoda Ku, Tokyo 1018430, JapanYokohama Natl Univ, Fac Educ & Human Sci, Hodogaya Ku, Yokohama, Kanagawa 2408501, Japan