An XY Playground in Classic 72


James Forest’s Classic 72 delivers two rare birds, then gets tripped up by a Y-wing.

The bypass threatens to take over, but leaves  an XY playground.

 

 

 

The line marked grid gives all of the Sysudoku Basic results.

Two fill strings of one value is a bit unusual.

The generous bv field predicts a productive XY railway system.

 

 

 

But first we look for UR, SdC, APE, and other methods not requiring maps and panels.

Here we have a classic indeed, an ALS toxic pair. The 3 value is contested, but 8r5c9 sees both groups of 8 that would be locked in by the winner.

 

Significantly, a 4-value Bent Almost Restricted n-Set, a BARN, can be superimposed around the ALS pair. Only the 8 values are bent. The removal is not as significant.

The significant removal is 6r1c4. It’s a 3-node XY-chain, adding  an NEr1 boxline removal and a naked triple in c4.

Collapse is immediate.

 

 

 

 

 

Next is Classic 96 (left) and 120. Both are solved in Basic.  Have your versions ready.

 

 

 

The Guide pages Sysudoku Basic, and Begin With the Bypass have been updated. If you’ve been putting off a serious evaluation, now is a good time.

Advertisements

About Sudent

My real name is John Welch. I'm a happily married, retired professor (computer engineering), timeshare traveling, marathon running father of 3 wonderful daughters and granddad to 7 fabulous grandchildren. The blog is about Sudoku solving. It covers how to start, basic solving to find candidates efficiently, and advanced solving methods in an efficient order of battle. It is about human solving methods, not computer solving.
This entry was posted in Basic Solving Procedures, Puzzle Reviews and tagged , , , , , . Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s