Reversed move

  You retro solvers amaze me, but I would probably not be able to prove I was sober,if asked to recite the alphabet in reverse. I was just curious if simply reversing one move from a puzzle would make a decent retro worth solving.                                                                                                                                               White has just moved, his opponent then tells him I was hoping you did not see the four move forced check mate you had on me,obviously you have lost, take back that move and I will show you what you missed.

    White takes back this move then checkmates Black in four forced moves.

That can't be right. In the diagram, white can checkmate black in 3 moves. Which means that white can do the same if you only take back Pa2-a3 (or many other moves)

The common assumption is that "mate in 4" also includes "mate in 3",  "mate in 2" and "mate in 1" so a short mate wouldn't count as a failure.

Usually in this type of retractor you would need to start in a position which requires more than 4 moves for checkmate. The retracted move improves the position for white such that the 4-move mate comes within his reach.

If White takes back his move, and the captured piece goes back on the board it will take white 4 moves. I just did this puzzle on tactics I seen the forced thee moves but was surprised by a piece that made it 4 moves.That made me wonder if it would be hard to find if you captured that piece. ...Maybe i should have asked what was the position of the board before white moved? 

That's a "vague" sort of problem. What you really mean is that you "hope" there is only one move reversal in a "normal" chessgame to lead to checkmate in 4 (and which we now learn must capture a piece).  I might be able to guess it but I'd rather give you a position which is not likely to be your solution to show that the instructions are insufficient.

LOL  that answers me if simply reversing a move in a puzzle or game makes a decent retro. I could have answered it myself if I gave it a little more thought.Tunnel vision is a hard habit to break,and certainly a minus in chess. Thanks for the input Ari 

You're welcome, sameez1. It's probably a good idea to start solving retro-problems to see how it works from the solver perspective. After that, it becomes much clearer what is expected from the composition. Not all retro composing is difficult. For instance, SPGs (Shortest Proof Games) only require the composer to find suitable forward moves. But may be it's not quite your thing.

hi are you good at chess