?? intersection homology of space with only 0-stratums singular .... ??? maybe some sort of "splicing" ??? .... ?? "moore-postnikov" ??? ..... ????? "lower half from upper stratums, upper half from 0-stratums" ??? ..... ??? .... ??? "mapping cone" .... ????? of map of spaces and/or of complexes ????? ... ??? ....