Thanks for the explanation Unike.

Done

Done

Difficulty score 22. No green.

Unlike, being a visual person, could you show an example of the block pincer or point me in the direction of s website to learn these advanced techniques.

start

ding

done

done

Phil - drwho's web page has a good write-up on advanced techniques. Plus if you use "advanced sudoku tips" to search google you will get plenty of sites. The biggest problem is the inconsistency in terminology. One person will call it a "pincer" another will call it something else.

Thanks KnightTime, that's very helpful.

Phil. Block Pincer is a technique I discovered myself, so I don't know another name for it or where it's pictured. It's difficult to draw here, but I'll try showing the most basic form. There are many variations.

The idea is, IF the upper left is a 6, then the lower right must also be a 6. And if so, then all those cells marked with B in the lower left are guarded against being 6. If that blocks 6 from being placed anywhere in the lower left block, then 6 must NOT be in the upper left.

(#,#)(#,6)(#,#) ...................(#,6)(#,#),(#,#)
....
....\n
....
(#,#)(B,B)(#,#)
(B,B)(B,B)(B,B)........\n.............(#,6)(#,#)(#,#)
(#,#)(B,B)(#,#)

Wish I could go back and edit. Somehow \n got in there.

go

Done.

done, ng

go

done

DING. Kind of slow going at first. 22.

Done