Mates that are difficult for engines

Ok Gentlemen, after looking at the "mate in 58" carefully I have determined that it is indeed longer than 58 moves even on the main line that was given (which ends up actually being a mate in 66), Arisktotle's idea of 2...Rg6 also seems to end up being a mate in 66, and finally MARattigan's idea 2...Kg5? results in a mate in 15 after 2...Kg5? which would actually be a mate in 17 from the root position if 2...Kg5? is played.. Thanks for pointing this one out to me so I could "fix it", hopefully it holds up now .

Here is my updated PGN:

Here's a mate in 23 before I go to bed.

White to move and mate in 23:

@drdos7 re #93.

If Black instead plays 8...Kg4 (in the main line) is there a quicker alternative than 9.Q3+ Kh4 10.Qf4+ Rf4 11.Qf6+ Rg5, reaching the position after move 9 but two moves later?

In your line I'm pretty sure you meant to say 9.Q3+ Kh4 10.Qf4+ Rg4 11.Qf6+ Rg5, 10...Rg4 instead of 10...Rf4, I'll let my computer think white's reply to 8...Kg4, but it looks like it does lengthen the mate by 2 moves in the main line.

Interestingly enough I found a mate in 62 that is the same as this one in the computer chess forums I go to except it starts later without the white pawns on f6 and g7 but we could only get it down to a mate in 64 at the time, it's the same position after the first 2 moves in my main line, I didn't have time to look at it because I had just found it this morning before I had to go to work, here is that one:

Yes indeed. Not very accurate was it? It should also have said 9.Qf3+. I should read what I've typed before hitting "post" or perhaps switch the light on. Sorry about that.

No problem, I've made FAR worse mistakes than that, and I knew what you meant because those seemed to be the only moves that made sense. Besides you did point out a flaw in my proposed main line.

Cool tactical shotgun

Mate in 14:

White to move and mate in 14:

Mate in 15

White to move and mate in 15:

first!

White to move and mate in 50:

Good luck engines.

Mate in 27.

Arena/SF15 and Tarrasch/SF15 fail to mate with 40 moves in 2 hours time control.

They fail most KNNvKP positions.

Don't really need an engine for this 😊

Oh wait I'm actually not sure what white does if blackmplays kf8 instead of h6, thought I solved it.

Some people do. You blew it on your second move. (Better than SF15 - it blows it on the first.)

Stockfish 15 announces a mate in 27 on my computer in 2 seconds for this position (with no tablebases loaded)

You can only be talking about move 3, but Kf8 is what you want him to play. Ne6 then corners him on h8. After Kh6 Black is still drawing; his mistake was 5...Kh7 instead of 5.Kf8.

I meant after ke6, the knight can't move to e6 at that point.

Sorry I was havering. You must be talking about move 5 and meant h7 rather than h6. 5...Kf8 is correct.

2.Ng6 and 5...Kh7 are both half point blunders in the sequence you show. The rest is fine.

The interesting thing here is that on my much slower computer Stockfish 15 doesn't find the mate in 27 at all.