Free online Chess server. Play Chess now in a clean interface. No registration, no ads, no plugin required. Play Chess with the computer, friends or random opponents.
Sign in
Reconnecting

Draws due to insufficient mating material

Asked by Bonifratz
Tags draw rules timeout insufficient material
Activity Viewed 5090 times, last updated
1
Sorry if this one has been answered before, but I couldn't find anything clear-cut in the Q&A:
What are lichess' EXACT rules on timeout draws due to insufficient mating material? From what I can gather, there are differing systems out there, e.g. FIDE's laws of chess require a legally possible mate, whereas USCF requires a legally possible FORCED mate in order for the time-out player to lose (and not get a draw).
Which of these variations (or other) does lichess use?
12 Answers
2
Answered by Bonifratz
The issue arises because it's not as simple as that. Consider KNN vs K. The side with two knights can't FORCE mate, but there are LEGALLY POSSIBLE mates in the position (if the opponent blunders seriously). So, if you run out of time with a lone king against an opponent with two knights, should you get the draw or lose the game?

FIDE and USCF rules differ slightly in this regard (see here for more: en.wikipedia.org/wiki/Draw_%28chess%29#Draws_in_timed_games).

I'd be interested to know which of these systems lichess follows.
2
Answered by Bonifratz
There are theoretical mates for White in KB vs KN (and thus also vs KP). Consider this continuation in your game (disregarding the nonsensical moves): 61...Kf3 62. Kb5 Ke2 63. Kc4 Kd1 64. Kd3 Kc1 65. Kc3 Kb1 66. Ba3 Ka1 67. Kc2 Nd4+ 68. Kc3 Nb5+ 69. Kc2 Nc3 70. Bc1 Na2 71. Bb2#.

Therefore, according to FIDE rules (the ones lichess uses), White wins if Black runs out of time.
2
Answered by ShowMeYourMoves
The incentives the FIDE system creates are bad for chess. I should have purposefully lose my last two pawn/pieces so I could draw. Makes no sense.
1
Answered by RealKool
I can't understand exactly, your title is about insufficient material, why you are mentioning mate? There is no mate in insufficient material.

Example.
KB vs K is insufficient, it is a draw even if you don't have time.
KN vs K too.
K vs K too.

But not KP vs K.
1
Answered by RealKool
For KNN vs K, it is a lose because the KNN are still capable to mate.
1
Answered by Bonifratz
Not according to USCF rules - they count KNN vs K as a draw if the K side runs out of time. Do you know for certain that on lichess this situation is a loss?
gaylord69 commented :
Yes I sacrificed my knight for a pawn and so the game could end in a draw yet the opponent with 2N was declared winer
1
Answered by umgambit
I just lost on time with KP v KN. Is it normal? King and Knight cannot mate, forced or otherwise. Shouldn't have my game ended with a draw ? Thanks!
1
Answered by Bonifratz
@umgambit: Yes, that's normal. There are possible mates with K+N vs K+B for example, so in theory the pawn could promote to a bishop and mate could happen. (This is not forced, but under FIDE rules it still counts as won as long as mate is theoretically possible.)
1
Answered by ShowMeYourMoves
Interestingly enough I just emailed contact@lichess.com who informed me that this game should have ended in a win for white even though its KB vs KP where there isn't even a possible mate on the board for white: lichess.org/Yke0jvXi

Their quote: "There's more than king+bishop vs king in your game. Both sides can checkmate."
1
Answered by LotBlind
So I just lost on time with KPP vs KB, and the KB was declared winner. I guess there's some theoretical way to arrange the pieces on the board so the KB mates the KPP, so is this what's supposed to have happened? I needed to sacrifice both pawns to make sure no theoretical mate exists?
Bonifratz commented :
Yes, exactly. Your game could *theoretically* continue 54. Kf6 Ba6 55. Ke7 Bb5 56. Kd8 Bc4 57. Kc8 Ba6+ 58. Kb8 Kd7 59. Ka8 Kc8 60. b7+ Bxb7# 0-1
Therefore, according to FIDE (and lichess) rules, Black wins when White runs out of time.
Had you lost/sacked both your pawns before running out of time, there wouldn't have been a legal way towards mate, so the game would've be declared a draw.

As @ShowMeYourMoves posted earlier in this thread, this rule creates bad incentives because in your situation it would've been advisable to throw away pawns (i.e. play suboptimally) just to draw.
On the other hand, the USCF rule according to which there has to be a *forced* mate has its downsides too, because a) it doesn't correspond well to a situation with more pieces on the board, which may well be drawn with correct play, but where a time-loss would automatically (and rightfully) be called a loss due to "sufficient material" on the board; and b) for on-the-board purposes it's a bit impractical because an arbiter can hardly be expected to correctly evaluate any given position.

I fear there's just no good way to adjudicate these situations so that it's fair, consistent, *and* practical in every case.
LotBlind commented :
Thanks for clarifying!
1
Answered by reza254
KN vs. KP and side with knight was declared winner after time was run out. Is this right? lichess.org/1zJvDNeBIXdF
Bonifratz commented :
Yes, this is 0-1 according to FIDE rules, because there's a theoretical (not forced) way to mate.
Example line: 75. Kc3 Kg6 76. Kd4 Nf4 77. Ke5 Kh5 78. Kf6 Kg4 79. Kg7 Kf5 80. Kh7 Kf6 81. Kh8 Kf7 82. h7 Ng6#
1
Answered by TheTap
Timeout with KN vs KP is always a win, even with a central pawn. The pawn can (theoretically) promote to a bishop, and then a mate can be constructed in a corner with opposite colour from the bishop.
The USCF rules requiring a forced mate seems quite subjective -- how is a timeout at the starting position judged? Do they consider the game drawn with best play? How do you prove there is (or is not) a forced mate?
Bonifratz commented :
I did some more reading and found that the USCF rules are actually quite clear, because the "forced win" exception only applies to three specific cases, namely 1) opponent has K+N, 2) opponent has K+B, 3) K vs K+N+N. In all three cases, if the weaker side runs out of time, a draw is called UNLESS there's a forced win on the board (I assume that arbiters use a tablebase in case they're unsure). This in turn implies that other cases are NOT treated this way, even when there's no forced win (e.g. K vs K+P+wrong coloured B); those will be called a loss for the weaker side. (The same applies to the starting position, obviously.)
See here: http://www.uschess.org/docs/gov/chessrules/US_Chess_Rule_Book_Chapters_1_2_11_v7.0.pdf, rules 14E2 and 14E3.

FIDE's rules, meanwhile, state that "the game is drawn if the position is such that the opponent cannot checkmate the player’s king by any possible series of legal moves." (www.fide.com/fide/handbook.html?id=208&view=article, article 6.9)
This limits the number of cases that are called a draw even further; the only such cases are: 1) opponent has lone king, 2) K vs K+N, 3) K vs K+B, 4) K+B vs K+B of the same colour.

Only registered members with one week of lichess activity can contribute to the Q&A.