Puzzle #552 - Penalty Heyawake

Something I've seen happen more often recent is genres to have some sot of "theory" developed for them, utilizing the underlying structure to prove something must be true within the bounds of a puzzle. One older example of this is Yin Yang never being able to have a checkerboard pattern, while the most well known recent examples are penalty and river Heyawake. These are pretty hard to explain and pretty hard to understand, though basic applications are fortunately approachable enough. Here are three explanations if you want to dig farther into the topic. I was pretty happy to find an antisymmetric construction for this grid size.

puzz.link interface

For this puzzle, the basic calculation will prove that there must be the maximum number of shaded cells on the edge and exactly zero loops of unshaded cells. In other words, 0 penalties or inefficiencies in the packing.