Hi,

MartinCHarvey!

MartinCHarvey wrote:I get up to 12199113 isomorphisms with 11 givens, at which point, a small refactor to use less ram is necessary.

Save myself the computation time and disk space, is there a "Group theory for dummies" textbook which I might find useful?

Please, use more precise terminology. "Isomorphism" is some kind of

transformation. But it seems you say about number of transformed

objects (grids, puzzles, etc.). It looks like you are saying about essentially different

patterns (9 x 9 binary matrices, where ones mark clue cells of 9 x 9 Sudoku puzzle).

Saying about textbook - I like textbook "An Introduction to the Theory of Groups" by Joseph J. Rotman (Springer series "Graduate Texts in Mathematics"). You should read chapters 1-3 only. Key theoretical concept - "Burnside's Lemma" (you can find it in Wikipedia too).

Serg