user10715: As an extension to this question about can a rook and knight without a king stalemate a opposing king, and the traditional minimum-mating-material question, I had a puzzle question:
What are the minimum combinations of material (without a king) required to forcibly mate an opposing king? 

R + R/Q is clearly sufficient
R + N + N/B maybe, as an extension from the above stalemate question

On the other hand, there are some sets that fail without a king:

B(w) + B(b) (but 3 bishops should work, so long as one is on a different color)


user10558: Assuming opponent has no pieces:

4 or more knights
4 or more bishops, at least 2 per side
At least 2 pawns, but it also depends on where the pawns are
2 or more major pieces
Queen and a minor piece
Rook and 2 minor pieces
4 minor pieces
Pawn+Minor pieces/2 Minor Pieces(depending on where the pawn is or a major piece

If opponent have pieces:

Queen(maybe rook)+Minor Piece vs 1 pawn
Queen(maybe rook)+2 pawns vs Rook+Bishop+Pawn
Q+R vs Rook and bishop or 2 minor pieces(for most positions)


10715: <p>As an extension to this question about <a href="https://puzzling.stackexchange.com/questions/36874/can-whites-rook-and-knight-without-moving-white-king-force-stalemate">can a rook and knight <em>without a king</em> stalemate a opposing king</a>, and the <a href="https://chess.stackexchange.com/questions/5028/what-is-sufficient-mating-material">traditional minimum-mating-material question</a>, I had a puzzle question:</p>

<p>What are the minimum combinations of material (without a king) required to forcibly mate an opposing king? </p>

<ul>
<li><p>R + R/Q is clearly sufficient</p></li>
<li><p>R + N + N/B maybe, as an extension from the above stalemate question</p></li>
</ul>

<p>On the other hand, there are some sets that fail without a king:</p>

<ul>
<li>B(w) + B(b) (but 3 bishops should work, so long as one is on a different color)</li>
</ul>
 10558: <p>Assuming opponent has no pieces:</p>

<ol>
<li><p>4 or more knights</p></li>
<li><p>4 or more bishops, at least 2 per side</p></li>
<li><p>At least 2 pawns, but it also depends on where the pawns are</p></li>
<li><p>2 or more major pieces</p></li>
<li><p>Queen and a minor piece</p></li>
<li><p>Rook and 2 minor pieces</p></li>
<li><p>4 minor pieces</p></li>
<li><p>Pawn+Minor pieces/2 Minor Pieces(depending on where the pawn is or a major piece</p></li>
</ol>

<p>If opponent have pieces:</p>

<ol>
<li><p>Queen(maybe rook)+Minor Piece vs 1 pawn</p></li>
<li><p>Queen(maybe rook)+2 pawns vs Rook+Bishop+Pawn</p></li>
<li><p>Q+R vs Rook and bishop or 2 minor pieces(for most positions)</p></li>
</ol>
