A General Logic for Sudoku

Monster #224 from list 1465

This is part of a set-logic solution to monster puzzle #224 from the 1465 list. The original solution to the puzzle (by ttt) was presented here. The elimination logic has the form:

rank N(n sets+ m linksets), [ cover set list ]x[ cover linkset list ] reason for elimination => results

For more information on notation and set logic eliminations, see quick reference. For a full description of sets and Sudoku set logic, see the SudokuOne.com website. The entire set logic solution is here.

Elimination 1, ALS Chain

This elimination works like a simple chain where one link is replaced by an ALS made of the two cell sets. Column set 9c3 overlaps 2 cell linksets 7n3 and 8n3 to eliminate the 2 candidates. The set logic notation is:

Rank 1(5+6), [9r3 2r7 6c3 16n2]x[129c2 78n3 9c3] 9c2*(78n3) => r78c3<>9