2 problems

Let $X$ be a PA-space, let $f$ be a PA-form on $X$, let $\Omega(X)$ denote the space of smooth differential forms on $X$, and let $P$ be a differential operator. Differential-opera…

Let $X$ be a reasonable topological space or a PA-space, and let $Y\subset X$ be a closed subspace. A map is a cofibration if it has the homotopy extension property. Cofibration co…