An effective bypass, and a simple uniqueness rectangle, and three choices to close down funster Extreme 116 early. Charles Timmerman’s funster Extreme collection is less than extreme, but a good introduction to advanced solving methods.
The basic work is easy, because the bypass does most of the heavy lifting.
Advanced 116 begins with a Type 1 unique rectangle. Candidate 1r6c8 is required to prevent an obvious multiple solution. The two candidates seeing it must go.
After a follow up of
there is a choice of three triggers for the collapse:
You have a border hugging XY nice loop.
Or a deceptively decisive Almost Nice Loop.
Or, if you’re a snapshot collector, or always do XYZ wings first, a regular 489-wing with a far seeing victim.
Our final funster selected for the review is Extreme 130. Review table next tim. The next review collection is Will Shortz’s Hard Sudoku, v. 1. Find the previous Shortz collection reviews on the Titles page. The latest new Guide page is about AIC Hinges, a topic way beyond Shortz.