2 papers
math.FA2019
On the ${\Ext}^2$-problem for Hilbert spaces
Félix Cabello Sánchez, Jesús M. F. Castillo, Willian H. G. Corrêa +2
We show that $\Ext^2(\ell_2, \ell_2)\neq 0$ in the category of Banach spaces. This solves a sharpened version of Palamodov's problem and provides a solution to the second order ver…
math.FA2018
Bilinear forms and the $\Ext^2$-problem in Banach spaces
Jesús M. F. Castillo, Ricardo García
Let be a Banach space and let denote the kernel of a quotient map . We show that $\Ext^2(X,X^*)=0$ if and only if bilinear forms on extend to $\el…