Answers.Body: <p>They aren't quite equivalent because of the differences in the position if White declines or partially declines the sacrifice (for example, after Nf2+ Rxf2 Bxf2, White doesn't have to retake the bishop - but after Bf2 Rxf2 Nf2+ declining the knight instantly loses the queen.)  But both should win, even if Bf2 is slightly better.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-04-03T16:40:51.287Z
Answers.LastActivityDate: 2017-04-03T16:40:51.287Z
Answers.UserDisplayName: D M
Answers.Body: <p>They're not <em>equivalent</em>, but your solution is just as good. In fact, it's more easy to find because Nf2+ is a 'forcing' move.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-04-01T20:38:53.453Z
Answers.LastActivityDate: 2017-04-01T20:38:53.453Z
Answers.UserDisplayName: Glorfindel
Body: <p>I saw the following puzzle recently in a newspaper:</p>
  
  <blockquote>
    <h2>Black to play and win </h2>
  
  <pre><code>6rk/6qp/2Bp4/P1pP1p2/3bnP2/6BQ/7P/5R1K w - - 0 1
  </code></pre>
  </blockquote>
  
  <p>My proposed solution was</p>
  
  <pre><code>1. ...   Nf2+
  </code></pre>
  
  <p>and the lines I foresaw were</p>
  
  <pre><code>2. Bxf2  Bxf2
  3. Rxf2  Qg1 mate
  
  2. Bxf2  Bxf2
  3. (something else)  Qg1+
  4. Rxg1  Rxg1 mate
  
  2. Rxf2  Bxf2
  3. Bxf2  Qa1+ and interposing B or Q only delays the end
  </code></pre>
  
  <p>However, the given solution was</p>
  
  <blockquote class="spoiler">
    <p> <pre>1. ...   Bf2!
  2. Rxf2  ...</pre>
   (If <code>2. Bxf2?  Nxf2+  3. Rxf2   Qg1 mate</code>)
   <pre>2. ...   Nxf2+
  3. Bxf2  Qa1+ and white resigns</pre></p>
  </blockquote>
  
  <p>I can see three possibilities:</p>
  
  <ol>
  <li>I missed something</li>
  <li>My solution is as good as the official one</li>
  <li>They're actually equivalent under transposition</li>
  </ol>
  
  <p>Which is the case?</p>
  
Tags: <analysis><puzzles>
Title: Is my solution to this puzzle wrong or a transposition of the official one?
ThreadText: # Is my solution to this puzzle wrong or a transposition of the official one?
  
  (Asked by: username_0 on 2017-04-01)
  
  I saw the following puzzle recently in a newspaper:
  
  > ## Black to play and win
  >
  > ```
  > 6rk/6qp/2Bp4/P1pP1p2/3bnP2/6BQ/7P/5R1K w - - 0 1
  >
  > ```
  
  My proposed solution was
  
  ```
  1. ...   Nf2+
  
  ```
  
  and the lines I foresaw were
  
  ```
  2. Bxf2  Bxf2
  3. Rxf2  Qg1 mate
  
  2. Bxf2  Bxf2
  3. (something else)  Qg1+
  4. Rxg1  Rxg1 mate
  
  2. Rxf2  Bxf2
  3. Bxf2  Qa1+ and interposing B or Q only delays the end
  
  ```
  
  However, the given solution was
  
  > ```
  > 1. ...   Bf2!
  > 2. Rxf2  ...
  > ```
  >
  > (If `2. Bxf2? Nxf2+ 3. Rxf2 Qg1 mate`)
  >
  > ```
  > 2. ...   Nxf2+
  > 3. Bxf2  Qa1+ and white resigns
  > ```
  
  I can see three possibilities:
  
  1. I missed something
  2. My solution is as good as the official one
  3. They're actually equivalent under transposition
  
  Which is the case?
  
  **Tags:** analysis, puzzles
  
  
  ---
  
  ## 2 answers
  
  ### Answer by username_2 on 2017-04-01. Score: 4 | Accepted answer
  
  They're not *equivalent*, but your solution is just as good. In fact, it's more easy to find because Nf2+ is a 'forcing' move.
  
  
  ---
  
  ### Answer by username_1 on 2017-04-03. Score: 2
  
  They aren't quite equivalent because of the differences in the position if White declines or partially declines the sacrifice (for example, after Nf2+ Rxf2 Bxf2, White doesn't have to retake the bishop - but after Bf2 Rxf2 Nf2+ declining the knight instantly loses the queen.) But both should win, even if Bf2 is slightly better.
  
  
  ---
  
  