Understanding Syzygy tablebases

Dear Community,

I need to understand how to read the Syzygy tablebases.

I use this webpage: https://syzygy-tables.info and there are two values which I do not understand: DTZ and DTM. What do they mean? I believe that DTM means how many moves to mate, is it like that?

However, if so, I have a question.

I gave this position to Stockfish 15.1 on my mobile: 8/8/4rk2/8/8/2K5/2Q5/8 w - - 0 1

The Syzygy says DTZ 41 and DTM 50.

However, Stockfish found a mate in 27.

Nalimov says that White can win in 26 moves.

So, how come Syzygy seems to be not so accurate?

Thanks and regards,

Giulio.

Zyzygy tablebases are not designed to find the fastest mates, just find the results based on the pieces on the board.

DTZ is Depth To Zero, the number of moves until the 50 move count resets.

The number next to DTM is a half-move.

Zyzyzg gives an additional piece, but my preference is the shredder data base if I do not require 7 pieces.

There are 3 metrics used in tablebases:

Depth To Mate (DTM) number of moves until checkmate.

Depth To Conversion (DTC) this one is the number of moves to a simplification to a different endgame. Such as a queen vs rook endgame where the queen captures the rook. It can yield slightly longer mates if for example it prefers capturing the rook first and then mating, even if there was a shorter mate with the rook still on the board.

Depth To Zeroing Move (DTZ) in endgames where a forced mate may take much longer than 50 moves without any pieces being captured or pawn moves, this tells it how many more moves until such a pawn move or piece capture will occur, resetting the count to 0, which can have implications for whether the 50 move rule is taken into account or not.