Coloring Dominates Very Hard III-15

The review of Moito’s Road to Mastery Sudoku continues with another example of early coloring and its cooperative interactions with the X-panel. The advanced path is similar to that of Very Hard I-35 two posts back, but this time coloring dominates the action.

When a first cluster stalls, a second one bids for attention by completely coloring the 8-panel, and delivers a column of traps.  Very Hard III-15 toughs it out as this dominant cluster grows, merging with its stalled predecessor. Finally,  the wrap of a third cluster chooses a side and its over. Sideshows to this drama are an irregular XYZ-wing and a finned X-wing that traps its own fin.

The bypass starts with a 3-fill, but then succeeds only in closing out the 9 placements. With one exception we’ve noted, Moito’s yield very little in the bypass, but tend to give up plenty of bv in basic.




A potential 57 UR in the North bank is prevented when the 4’s insist on a place in one of the roof corners. A second possible UR is erased by the r7 naked triple.




Next, the XYZ map reveals an irregular 675-wing. The 75 wing is attached with an 7-chain, in which two slinks function as winks for the team.

As Very Hard I-35 suggested, it’s a good idea to start coloring clusters when bv are abundant. On the ©PowerPoint grid template they don’t interfere and later unrelated removals can bring traps or wraps in the clusters.



The finned 6-wing removes 6r4c4, making 4r5c4 and 6r4c4 red, trapping the 6-wing’s fin, 6r6c4. That’s the advantage of having a coloring network in place. And it is so easily done.

Two more traps and green merges into red, blue into orange.


One more trap and we are dangerously close to a BUG, a double solution certified by unanimous bv.

One final cluster saves the day, as 4r8c2 is trapped, seeing orange and red, wrapping Aqua. Lavender sees orange, so red wins.



While Moito’s Road to Mastery is not consistently advanced in practice, or in protection from multiples, it has provided many entertaining challenges. I think it deserves to finish out the January posts. So let’s do Very Hard III-34 next time.

The Guide pages now cover Sysudoku Basic. If you’re a beginner, it’s all you need for know, for now.

Stay tuned, the Sysudoku Advanced header page is completed. The Unique Rectangles methods page  is next.



About Sudent

I'm John Welch, a retired engineering professor, father of 3 wonderful daughters and granddad to 7 fabulous grandchildren. Sudoku analysis and illustration is a great hobby and a healthy mental challenge.
This entry was posted in Advanced Solving, Puzzle Reviews and tagged , , , , , . Bookmark the permalink.

Leave a Reply

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

You are commenting using your 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