6:27 CET

Remember me

 Rating ListJanuary 1st2013

MatPlus.Net Forum General Concurring Mates

### Concurring Mates

It's a bit embarassing - I make 2# since decades and still
don't know what concurring mates (konkurrierende Matts) are.
(How could I, googling gave 0 hits :-)
Explanation get bonus points if using one of my own crimes :-)

Hauke

a concurrent mate is a mate when compared to another mate is along the same attacking line. This concept is generally found in changed play, where a wQ, for example will mate on a1 in one phase and b2 in another, let's say attacking a king at f6.

J.Kiss, 1 Prize, Hungarian Problemists' Theme Tourney 1942

Set:
1... Kd6 2.d8Q
1... Kf6 2.f8Q
1... Kd8 2.Qg5
1... Kf8 2.Qc5

1.Qe4! zugzwang
1... Kd6 2.f8Q
1... Kf6 2.d8Q
1... Kd8 2.Qh4
1... Kf8 2.Qb4

John Rice in 'Chess Wizardry: The New ABC of Chess Problems', said: "The changes following the king's moves to d8 and f8 are of a type known as concurrent: the queen merely mates on a different square but on the same line in relation to the black king. Such changes are held to be slightly inferior to a more complete alteration of the mating position."

TIL. THX.

Hauke

Thanks Geoff Foster for showing this wonderful problem of Janos Kiss. In addition to showing the four changes after the BK star flights, it also shows a reciprocal change and is a mutate. Interestingly the problem can be solved again after the key and the solution will be the queen reverting to old position !

Hm, nobody grumps about the possibility 2.f8B,d8B in solution.
Looking at the theme of this thread I'd prefer to call such mates "korrespondierend" ("correspondent").

I think the English word "concur" is a "false friend" for us Germans. It is not "konkurrieren" (although it looks similar) but, almost in the opposite direction: "zusammentreffen, zusammenwirken, übereinstimmen" (well, "run together" from Latin, but not in the sense of a competition to see who is the fastest). Maybe "gleich wirkende Matts" or "gleichartige Matts" or "gleichgerichtete Matts" or "richtungsgleiche Matts"?

in #2s there is no distinction between Q/B and Q/R on the mating move. it is simply Q and S.

I know, but here in setplay the promotion is unique, but not in solution. Nevertheless a very impressive problem.

in french, "concourant" means "alike" for example "une erreur coucourante" "almost the same mistake"
It seems, in my dictionary, that concurrent, in english, has the same meaning as "concourant" in french.

@Hartmut: Aha! Today I learnt again. (In German I read this term
always only in the false friend translation. No wonder I never knew
what was meant.)

Hauke

Simplified and imprecise definitions can be misleading (even for the experts). I would appreciate some clarification, in general and in this particular case. Here is what I see as a laic.
According to the Codex, d8Q/B# IS A DUAL but it is tolerated as regards the general soundness/correctness. That does not mean that each sound problem is thematically pure. d8Q and f8Q/B are different moves so the essence of the changed mates is present. d8Q & f8Q are not the same as d8Q/B & f8Q/B so the essence of a RECIPROCAL change is NOT PRESENT. It is not about the tolerable duals here, promotions to Bishops are perfectly legal and they also solve the problem without reciprocal change. To accept the reciprocal change in this problem, the Codex should be changed, for example:
When #1 is possible by a promotion to Q, all minor promotions are considered as illegal. Or more convenient for AUW - when #1 is possible by a promotion to R or B, the promotion to Q is considered as illegal.
(But there is a reciprocal change of the Pawns which promote and mate)

@ Nikola

In the meanwhile, there is no definition of exchanged mates in the codex.

In orthodoxe 2# there no case where a mate is necessarily 2.X=B# or 2.X=R#, so the common usage is to forget simply these possibilities.

It's right that there is a slight difference in 2.X=Q# when a Q is mandatory or not. But the reason why generally people don't care is quite understandable.

The same is for the 1st black move : 1...X=B, or 1...X=R cannot have a practical use, so for the same reason, a try refuted by 1...X=Q/B! or 1...X=Q/R! is generally seen as a usual try with one refutation.

Dualistic promotion is a 'tolerable dual', but it remains dual - both promotions are equally possible and usefull. d8Q is one move, d8B another and d8Q/B is a tolerable dual - a special possibility, obviously different in nature than both of the first two. I tolerate dualistic possibility of minor promotion but this possibility can not disapear when it is convenient for someone's common usage.

(15) Posted by Hauke Reddmann [Wednesday, Feb 1, 2012 15:53]

Depends, depends. Whereas Judge Petkov found a fault with
the promotion duals in my MatPlus708 (absolute justly,
since the theme was a promotion cycle and the possibility
h8Q/R was annoying) in the above Kiss problem I tend to
tolerate it too, but would at least have swapped solution
and set play. It would be interesting to learn the judges
comment on the Kiss problem.

Hauke