We provide a general preservation theorem for preserving selective independent families along countable support iterations. The gives framework number of results in the literature concerning models which independence i is strictly below c, including iterations Sacks forcing, Miller partition h-perfect tree forcings, coding with perfect trees. Moreover, applying theorem, we show that i=ℵ1 Lite m...

Em 1950, Leonard Cohen encontrou numa livraria uma tradução dos poemas de Federico García Lorca. Anos depois, afirmou que desejava responder àqueles poemas, pois eram espécie chamado a pedir resposta. Nesse sentido, podemos ler obra como tentativa à poesia lorquiana, emulá-la partir um imaginário comum. Tendo isso em vista, este artigo visa, primeiramente, identificar presença topoi da Lorca na...

Let G be a simple undirected graph on n vertices, and let I(G) ⊆ R = k[x 1 ,. .. , x n ] denote its associated edge ideal. We show that all chordal graphs G are sequentially Cohen-Macaulay; our proof depends upon showing that the Alexander dual of I(G) is componentwise linear. Our result complements Faridi's theorem that the facet ideal of a simplicial tree is sequentially Cohen-Macaulay and He...

We study properties of a poset generating a Cohen-Macaulay algebra with straightening laws (ASL for short). We show that if a poset P generates a Cohen-Macaulay ASL, then P is pure and, if P is moreover Buchsbaum, then P is Cohen-Macaulay. Some results concerning a Rees algebra of an ASL defined by a straightening closed ideal are also established. And it is shown that if P is a Cohen-Macaulay ...