-3

"Berserk king" is my own invention ;). It means that you play according to the normal chess rules, until a king is mated. At that point the mated king is allowed to do TWO moves, in a last attempt to save his life. The first move does not have to be legal of course: as per the definition of mate, he will still be in check after the first move. And its second move may capture the enemy king which will even win the game for the berserk king!

The question now is: make a position that can clearly be achieved with the normal rules and then show how you can mate the black king from that position such that you win even if the king goes berserk. During those last moves no pawns may promote or pieces be taken.

For example, the following position won't be accepted:

[FEN "7k/4K3/8/6RQ/8/8/8/8 w - - 0 1"]

because there is no way to reach this position with optimal counter play of black. Playing backwards from this position must uncheck black, and give him space that he could have come from. There is no such backwards move that will force black to go stand in the corner however.

Likewise, the following position - although berserk-mate is not acceptable:

[FEN "7k/4KRQ1/8/8/8/8/8/8 w - - 0 1"]

because it would only be reachable if the white queen took a black piece on its last move.

Finally, the follow isn't correct either:

[FEN "6k1/5R2/5K2/4R3/8/4N3/8/8 w - - 1 0"]

1. Nf5 Kh8 2. Re8#

because, although black can't escape check in two moves; they can capture the white king and win! Not berserk-mate thus.

The question is, what position can you come up with that has the least number of points on the board, from which you can reach a berserk-mate without capturing pieces or promoting pawns? That is, Queen=9, Rook=5, Knight=3, Bishop=3 and pawn=1 point.

The best that I could come up with so far (although I didn't try very hard: it has to remain an achievable challenge to improve it ;) is:

[FEN "5B2/4KP1k/8/8/8/8/8/6R1 w - - 0 1"]

1. Rg2 Kh8 2. Rg6 Kh7 3. Rf6 Kh8 4. Rh6#

at 9 points, where no two moves of the black king can bring it out of check or capture the white king.

EDIT:

As a fun side-note - if the position doesn't have to be reachable (but it should be in order for it to be a correct "answer" to this question) then the following would be a solution with just 3 points:

This is mostly a reaction to @DialFrost 's comment, asking if the position has to be "reachable", at which I stated that it could be an interesting question to ask for any position, as long as white can force berserk-mate in at least -say- 3 moves; without that white is allowed to promote (which would be a higher number of points imho).

Here is what I came up with, for that case: berserk-mate in 6 with 3 points :P

[FEN "1b1b1b1b/b1b1b1b1/1b1bKb1b/b1b1b1b1/1bBbkbpp/b1b1b1bp/1p1p1p1b/1n1n1nb1 w - - 1 1"]

1. Ba6 Kf3 2. Kf5 Kg2 3. Ke4 Kh1 4. Bd3 Kg2 5. Be2 Kh1 6. Bf3+
5
  • Yay for the anonymous down voters. Care to add what exactly makes this question "bad"? Especially after the "chess-variants" tag was added (thanks for that), I don't see a reason to down vote it just because you don't like it. The reason should be that the question is unclear, ambiguous, etc. In which case you should add a comment and give me the chance to improve the question.
    – Carlo Wood
    May 1 at 11:45
  • I don't understand the problem with the second position. What's wrong with white taking a black piece to checkmate? It's also confusing that you say "During those last moves no pawns may promote or pieces be taken." when of course the white king may be taken... May 2 at 5:02
  • @SteveBennett "No pieces may be taken" refers to the moves leading up to the mate. Black optionally capturing the white king is after that, and more of a virtual move (you could explain a normal mate also with: no matter what move black does, white can take the black king afterwards; even though no kings are taken and the game simply ends after a king has been mated). The second position is not reachable without -very recently- a piece capture and is therefore not accepted as solution. You could argue that this rules make no sense though and create a different problem stating that only white
    – Carlo Wood
    May 2 at 9:43
  • may not promote, and no white piece may have been captured in the last few moves. Probably I should have formulated it better, but I had just came up with this- so it wasn't all that clear even to myself :P. Currently I think the best problem statement is that white must be able to force back into berserk-mate while arbitrarily long no pieces are captured (and no promotions happen). This to emphasis that white has total control over the situation and can "toy" with black as long as they want. In the case that white takes a black piece in the last move before the berserk mate it appears to me
    – Carlo Wood
    May 2 at 9:49
  • that black could have avoided the berserk-mate by playing differently in the move leading up to the final position, and therefore it isn't a REAL berserk-mate in the sense that black cooperated with it (or made a stupid mistake) not too long before the mate happens (of course black made a mistake somewhere in the game, or he wouldn't be losing this bad).
    – Carlo Wood
    May 2 at 9:51

4 Answers 4

1

All combinations found below make use of the quadruple pawn structure on the top left side of the board

7 points (bishop)

[FEN "4K1k1/8/5PP1/4BPP1/8/8/8/8 w - - 0 1"]
[Startply "25"]

1. Ke7 Kh8 2. f7#

7 points (Rook)

[FEN "7k/R7/5PP1/6K1/8/8/8/8 w - - 0 1"]
[Startply "25"]

1. Ra8#

9 points (Knight combo)

[FEN "6k1/4K3/5PP1/4NP2/6N1/8/8/8 w - - 0 1"]
[Startply "25"]

1. Nh6+ Kh8 2. Nef7#

10 points (Bishop combo)

[FEN "6k1/3BK3/5PP1/4BPP1/8/8/8/8 w - - 0 1"]
[Startply "25"]

1. Be6+ Kh8 2. f7#

11 points (Queen)

[FEN "8/4KP1k/5P2/4Q3/8/8/8/8 w - - 0 1"]
[Startply "25"]

1. Qg5 Kh8 2. Qh5#
4
  • But how did you reach this position? Got to show a couple of moves that prove that black had no other choice. Well, I can see how I guess. Last moves 1... Kg7-h8 2. Be7-f6#
    – Carlo Wood
    May 1 at 10:23
  • 1
    Yup, looks all ok! Now try to reduce the number of points of white below 9, and add a few more moves in the PGN to show that one can reach the position in a real game with just those points.
    – Carlo Wood
    May 1 at 11:37
  • @CarloWood I managed to get it to 7 points! Is it valid?
    – DialFrost
    May 1 at 13:43
  • 1
    I don't think so. The rook at least, what was blacks last move? And why did he go to the corner? I think he could have gone to f8 instead.
    – Carlo Wood
    May 1 at 17:46
1

8 points, acceptable?

[FEN "5k2/3PR3/5PP1/6K1/8/8/8/8 w KQkq - 0 1"]

Wait for Kg8 (say Re6), then Re8#

EDIT: Think I'm down to 6:

[FEN "6k1/4P3/5PP1/6K1/3B4/8/8/8 w KQkq - 0 1"]

Wait for Kh8 (say Ba1), then f7#

5
  • Yup, that will do it ;).
    – Carlo Wood
    May 1 at 10:24
  • Awesome! The 6 pointer definitely satisfies the "white toys with black" 'requirement' (as I just added/stated in the comments as reaction to Steve Bennett) in that white can wait a while by doing arbitrary bishop moves before he delivers mate. I think now it is time to admit that the reason I posted this was to see if anyone would be smart enough to add black pieces in order to lower the points of white. Since you are Hauke I have to assume less than 6 points isn't possible :-D as long as there is just a single black king.
    – Carlo Wood
    May 2 at 10:02
  • I did post a "solution" with 3 points already that hint this, but that position is unreachable in a normal game. You think you can go below 6 when adding black pawns? Lets keep the "white toys with black" requirement in that case though; if it was trivial for black to escape the berserk-mate by moving -say- one of his pawns, then it's clearly a cooperative mate, which I am definitely not interested in.
    – Carlo Wood
    May 2 at 10:03
  • I now editted my question and added that position as a "fun side note" at the end. I hope that is allowed (or I'll leave this site for having moderators that don't get their priorities straight). So, please scroll to the bottom of the question to see the position I was referring to.
    – Carlo Wood
    May 2 at 10:15
  • @CarloWood: Yup, the old gag with the bishop-plastered board :-) Here is a legal solution with four points and promoted black material (I doubt that a legal with three is possible): Kd7 Bh1 Pb5, Kb7 Ba7 Bb8 Pc7 Pb6 Pc6. That is, if you forego "infinite delay", a three point solution based on the smothered mate is easily possible: Kd1 Nc2, Ka1 Pa2 Pb2 Rb1 Bc1 Pd2 (the K can't jump onto his pieces, right?). But the mate can only delayed by the number of spare pawn moves (say, add a bPa7). May 2 at 14:46
0

Another one with 7 points, 2 of which are black's.

After f7+, Kh8, you matemate in the position below with f8=R##

[FEN "7k/4KPpp/8/8/8/8/8/8 w - - 0 1"]
2
  • I violated the no-promotion rule. No matemate, mate.
    – starrin
    May 1 at 13:37
  • Plus, this looks like a cooperation mate; black would play his pawns and not wait until he was mated.
    – Carlo Wood
    May 1 at 17:45
0

I didn't want to spoil it for others, but apparently I have to post REAL answers only to my own questions. Oh, well, I guess enough time passed. This was a challenge to see if people would be smart enough to add black pawns.

Here is my solution:

[Variant "From Position"]
[FEN "N6b/8/8/6pp/6pk/6p1/6P1/7K w - - 0 1"]

1. Nb6 Bd4 (1... Be5 2. Nd5 Bf4 3. Ne7 Bc1 4. Nf5#) 2. Nc4 Bc3 3. Nd6 Ba1 4. Nf5#

White can toy with black as long as he wants (postpone the mate) during which no promotions happen en no pieces are taken. But eventually black can never stop white from delivering mate, which happens to be a berserk-mate due to the fact that the black king can't capture the white knight in two moves: he is blocked by his own pawns.

1
  • a) you might the save the wP: Kg1 Na8, Kh5 Bd5 Bh4, Pg6...g2,Ph6, but b) are you sure the N can bring the B into zugzwang (and not the other way round)? (At least my solving program even mated with +bPh2, nailing the wK put, and asserted a) isn't solvable, so yes, your record still stands. :-) May 2 at 15:02

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