cohomology ring of a simplicial complex

[micjoswig]

Code for (integral) cohomology of simplicial complexes is in the making, to be merged very soon. Main functions inherited from polymake.

Yet these are only the abstract groups (or ZZ-modules). There is an additional structure as a graded algebra, which OSCAR should eventually have, too. That algebra has the property $p q = (-1)^{i+j} q p$ for $\deg p = i$ and $\deg q = j$. So it is an associative algebra which is "almost commutative".

This requires to have the generators (as simplicial chains). Again polymake does have that. They are not computed by default as that is much more expensive than computing the mere groups.