This continues the review of Will Shortz’ Hard Sudoku v.1, with another documented basic finish. Starting the Guide? Accounting for each move in this series, then trying them beforehand, will make Sysudoku basic yours.
Beware 175 matches 165’s collapse point, but with slightly different triggers, a boxline and a naked pair.
The box/line interaction, or boxline, occurs when marking line r5. No 9 candidate appears in r5 outside the East box, so the true 9 is in r5. The other E9 hopefuls must clean out their desks, and leave the building.
The naked pair begins the collapse.
Next week, its Beware 185. The Hard Sudoku v.1 review ends with 195, then my plan is return to earlier reviews to update all review posts to Guide methods and drawing conventions, with weekly post reporting on changes. The earlier posts will remain accessible through Title and Find It pages, and the monthly archive pages. New collection reviews can be undertaken on reader request.
The first review update is half done. It is the KrazyDad Insane collection, beginning mid July 1013.