ghfick wrote:I am unsure of the boundaries between the levels of difficulty. I think your intention was to use equivalents to the default boundaries in HoDoKu but now using the original SE ratings. What is the boundariy between Extreme and Insane?

Dim Shared As Long difLevel(0 To 6) = {0, 15, 28, 60, 80, 93, 120}

Use SKFR ,the grading boundary is as above.

ghfick wrote:Here are a few more suggestions and queries:

May I suggest adding the SK Loop? It is true that the SK Loop can overlap considerably with MSLS. pjb has noted that there are puzzles where the two steps can give different exclusions though. The logic is quite different though.

When I have time, I will implement it. In fact, I wrote SK_Loop in the previous version of VB6.

ghfick wrote:With your implementation of JE, there are the interesting cases where additional cells can be added to the "S" cells to confirm the JE pattern. Currently the solver says: ' "S" Cells Need Include xxxx True Base Cands xxxx'. I think this needs rewording. The additional cells are not "S" cells and there are no known True Base Candidates [I am unsure what is intended here?]

Since there are Naked Quads and Hidden Quads, can there be Almost Locked Quads? Maybe such an ALQ step is getting too close to Sue de Coq or ALS-XZ? The logic would be different though.

One receives the Avoidable Rectangle in solution paths. It should listed in 'Techniques'. Recent forum discussion on the AR may be relevant. [UR 1.1]. Alas, I understand very little of that discussion.

It is not complicated for a computer to detect a base candidate as follows. If it appears in the base cell, and it is assumed that the target cells does not have it, and then enumerate the positions in the cross line. If a house will miss the number in all the above situations, it is proved that as long as the number appears in the target cell at the base cell at the same time.