Witt space

A rational Witt space is a stratified pseudomanifold such that the link $L$ of every stratum of odd codimension $2r+1$ satisfies $I{H}_r^{\bar{m}}(L;\mathbb{Q})=0$. This removes the only difference between lower and upper middle extensions and gives rational middle-perversity Poincare duality on closed oriented Witt spaces.

A compact stratified space with boundary is a Witt space with collared boundary when its interior and boundary are Witt spaces and a stratified neighbourhood of the boundary is $\partial X\times [0,\epsilon )$, with product stratification. Orientations are carried by the regular strata and induce the usual boundary orientation.