Description of posets critical with respect to the nonnegativity of the quadratic Tits form

• Date: 2009
• Main Authors: Bondarenko, V. M., Stepochkina, M. V., Бондаренко, В. М., Степочкина, М. В.
• Format: Article
• Language: Russian; English
• Published: Institute of Mathematics, NAS of Ukraine 2009
• Online Access: https://umj.imath.kiev.ua/index.php/umj/article/view/3045
• Journal Title: Ukrains’kyi Matematychnyi Zhurnal

We present the complete description of finite posets whose Tits form is not nonnegative but all proper subsets of which have nonnegative Tits forms. A similar result for positive forms was obtained by the authors earlier.