user-1: This is quiz 24 from The Art of the Checkmate by Renaud & Kahn.
Black to play and win
rn3rk1/pp3ppp/3b1n2/2pPq3/2B1P3/1NN2bP1/PPPQ1P1P/R1B2RK1 b - - 0 1

The authors give this as the winning line:

 1... Qh5 2. Be2 (as Black was threatening Qh3-g2#) Ng4 (threatening mate on h2) 3. h4 Qxh4 4. gxh4 Bh2#

However, I think White has a simple refutation:

 2. Re1 prepares Bf1, stopping the Qh3-g2 threat, and Ng4 threats can be nullified with h4, as the Queen sacrifice doesn't work now as the King has a flight square

So, my questions are:

Is there a forced win (mate or material)?
If so, what is it?
If not, what's the best move?


user7297: Yes, you're right, there is no forced win. With correct play, White avoids the mate, and Black can only win one of the two pawns he is currently behind. White will have a healthy pawn more with best play from both sides:
rn3rk1/pp3ppp/3b1n2/2pPq3/2B1P3/1NN2bP1/PPPQ1P1P/R1B2RK1 b - - 0 1

1... Qh5 2. Re1 Ng4 3. h4 Ne5 4. Bf1 Bxe4


-1: <p>This is quiz 24 from <em>The Art of the Checkmate</em> by Renaud &amp; Kahn.</p>

<p><strong>Black to play and win</strong></p>

<pre><code>rn3rk1/pp3ppp/3b1n2/2pPq3/2B1P3/1NN2bP1/PPPQ1P1P/R1B2RK1 b - - 0 1
</code></pre>

<p>The authors give this as the winning line:</p>

<blockquote class="spoiler">
  <p> 1... Qh5 2. Be2 (as Black was threatening Qh3-g2#) Ng4 (threatening mate on h2) 3. h4 Qxh4 4. gxh4 Bh2#</p>
</blockquote>

<p>However, I think White has a simple refutation:</p>

<blockquote class="spoiler">
  <p> 2. Re1 prepares Bf1, stopping the Qh3-g2 threat, and Ng4 threats can be nullified with h4, as the Queen sacrifice doesn't work now as the King has a flight square</p>
</blockquote>

<p>So, my questions are:</p>

<ol>
<li>Is there a forced win (mate or material)?</li>
<li>If so, what is it?</li>
<li>If not, what's the best move?</li>
</ol>
 7297: <p>Yes, you're right, there is no forced win. With correct play, White avoids the mate, and Black can only win one of the two pawns he is currently behind. White will have a healthy pawn more with best play from both sides:</p>

<pre><code>rn3rk1/pp3ppp/3b1n2/2pPq3/2B1P3/1NN2bP1/PPPQ1P1P/R1B2RK1 b - - 0 1

1... Qh5 2. Re1 Ng4 3. h4 Ne5 4. Bf1 Bxe4
</code></pre>
