My question is on the example below, taken from page 4 of http://www.math.wisc.edu/~andreic/publications/lnPoland.pdf.
I'm not familiar enough with this stuff yet to understand why the quasi-isomorphism below does not have an inverse.
I'm also caught up on the second example since I don't understand what the map $(x, y)$ means. Is that projection from the first part of the direct sum onto $\mathbb{C}[x, y]$?
I would be appreciative if anyone here could work out the details on these examples.
