I revived my old favorite method for extremely difficult puzzles and solved the December 3 expert.

The method is systematic removal of greens. Choose a cell with at least three greens and test each green in turn. Remove all greens which produce conflicts.

If none of those tests solve the puzzle, move on to another cell with at least three greens and do more testing. Repeat as necessary.

easier expert today, first guess

TallMike: I use a similar method along with hidden pairs, line blocks, anything I can. This Expert seemed a little easier, but still a great challenge.

I use an iPad because of my poor vision. As far as I know, there is no way to use greens. So my method is to find all the pairs and then construct some chains like an XY wing or a coloring. That usually works but is sometimes tedious.

I agree, still a challenge and tedious but TA DA I have solved it!

I do not know whether there is a name for the method I described yesterday for solving extremely difficult puzzles. My suggestion is Pick the Lock. The method is of course only useful if you first apply all the easier techniques you know and find yourself stuck. Thanks Limer for specifically pointing that out.

TallMike - on extremely hard puzzles, I look for 3 pairs of numbers, e.g. 3,7 7,9 9,3 in the same row or column and then see if a choice of one of the numbers say 9 causes a logical inconsistency. If there are no sets like that, then I move up to quadruple sets and try.