This post reports a series of Beeby ALS-XZ featuring alignments in Z and X, almost to the point where a trial is needed.
A simple basic trace means a hard start, with a crowded grid.
Sudokuwiki’s 579-wing is a Beeby ALS _97. Both solvers do it twice, because nobody codes a second look for victims.
Next we get a digit forcing chain boomer from 1r6c1.
Rendered by Beeby as a overlapped ALS-wing. Can you follow the money?
Now Beeby continues the ALS clinic with an ALS 4_3 with grouped X and grouped Z,
an improbably aligned ALS-wing,
then another one equally improbable.
Using Phillip Beeby’s solver, you choose the method category on each step, so the order of methods found can be subjective. Sudokuwiki imposes its own order.
Now after a series of ALS, Beeby runs to exhaustion with AIC.
First is a relatively simple complex 1-way starting a 6 r2c6 with a single branch to manufacture a 1-way slink. It’s ending 6r3c8 happens to see two victims. This isn’t done twice. Beeby notes both in the chain description drawn for you. You’re welcome.
Then you get a more complex 1-way, starting at 1r6c1 and sporting three branches.
Looking at this, you realize there is no definable boundary between practical and impractical human human solving.
Sysudoku readers know exactly how to find such a thing, but they have a life, so its likely that nobody will.
Let’s leave the rest for next post. Start with the hidden UR that leaves the techniques of this review exhausted. Then decide on a trial from the repertoire of this review and go for it. Or meet that challenge we started the review with, an ultrahardcore right page solution without trial.
Or do some homework on the last review puzzle, ultrahardcore 487.
Systematic Sudoku 