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 15, Simple Chain

This logic is a simple chain or discontinuous nice loop that eliminates the candidate 4r7c2. This leads to the assignment of 4r3c2 and several subsequent eliminations. The set logic notation for the elimination is:

Rank 1(4+5), [2r7 6c3 4c5 8n7], [4r7 46r8 7n23] 4r7*7n2 => r7c2<>4

=> 4r3c2 => r3c2<>19, r3c3<>4 => 9r3c3 => r3c3<>18 r79c3<>9, r5c7<>2

=> 8r3c7 => r3c7<>6, r3c4<>8=> 7r5c7 => r5c9<>7, r9c7<>7 => 7r9c9 => r9c9<>1349