INF - Artigos publicados em periódicos
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Navegando INF - Artigos publicados em periódicos por Autor "Assem, Ibrahim"
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Item A note on fundamental group of a one point-extension(2005-05) Assem, Ibrahim; Bustamante, Juan Carlos; Castonguay, Diane; Novoa, CristianIn this note, we consider an algebra A which is a one-point extension of another algebra B and we study the morphism of fundamental groups induced by the inclusion of (the bound quiver of ) B into (that of ) A. Our main result says that the cokernel of this morphism is a free group and we prove some consequences from this fact.Item Strongly simply connected schurian algebras and multiplicative bases(2005-01) Assem, Ibrahim; Castonguay, Diane; Marcos, Eduardo do Nascimento; Trepode, Sonia ElisabetIn this paper, we define concepts of crowns and quasi-crowns, valid in an arbitrary schurian algebra, and which generalise the corresponding concepts in an incidence algebra. We show first that a triangular schurian algebra is strongly simply connected if and only if it is simply connected and contains no quasi-crown. We then prove that the absence of quasi-crowns in a triangular schurian algebra implies the existence of a multiplicative basis.