Answers.Body: <p>I think it is useful in these sorts of problems to categorize moves.  You say that Re5 looks promising, but that there are too many moves for black afterwards.  I would work through this as follows:</p>
  <p>What's good about Re5? It prevents the opponent's king from moving, shrinking the possibilities we need to consider.  The threat is 2. Rc5#, but this is prevented by black's knight.  If knight moves, 2.Rc5# will be possible because there are no checks.  If pawn moves Rc5# remains impossible and no other mate presents itself.</p>
  <p>Note that I don't need to consider where the knight is moving <em>to</em>.  Since we know our threat after Re5 all we have to consider are moves that prevent that threat from working. d2 is such a move, and tells us that Re5 doesn't work.</p>
  <p>To find the correct solution, we need to find a different solution to 1... kb5 or kd5.  Blocking with the rook of queen like you've proposed doesn't work, so we have to instead look for situations where those moves are mate in 1.  This leads us to realize our bishop being in the way is a serious problem, which motivates 1. Bb6, which is indeed correct.</p>
  
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Answers.CreationDate: 2020-12-23T06:55:29.743Z
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Answers.Body: <p>With the rook on e5 to start, there are a number of mates in 2 as discussed. However, with the rook on e6, Bb6 is mate in two. For instance</p>
  <ol>
  <li>Bb6 d2 2. Qb3 mate
  or 1. ... N any 2. Qc5 mate
  or 1. ... Kc3 2. Qc1
  or 1. ... Kc5 2. Qxd3
  or 1. ... Ke4 2. Qxe4</li>
  </ol>
  
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Answers.CreationDate: 2020-12-23T18:13:25.657Z
Answers.Text: Wow lichess doesn’t see it! A plus 1 for you!
Answers.UserDisplayName: fartgeek
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Answers.CreationDate: 2021-06-12T14:49:32.667Z
Answers.Text: @fartgeek Yeah, "Lichess" [does](https://lichess.org/analysis/8/8/4R3/8/2kBn3/K2pQ3/8/8_w_-_-_0_1) see it, in the blink of an eye.
Answers.UserDisplayName: Mobeus Zoom
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Answers.Text: @MobeusZoom not on depth 18…
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Answers.Text: @fartgeek Doubt that's possible, depth 18 vs depth 25 makes no difference in spotting a #2. (It only changes eval 19+ moves down the line.)
Answers.UserDisplayName: Mobeus Zoom
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Answers.CreationDate: 2021-06-13T23:58:57.983Z
Answers.Text: @MobeusZoom You are lacking a critical understanding in how search depth works. I recommend you peruse an article germane to this subject…
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Body: <pre><code>[FEN &quot;8/8/4R3/8/2kBn3/K2pQ3/8/8 w - - 0 1&quot;]
  
  1. Re5?
  </code></pre>
  <p>With White to move, here is a mate in two problem that I couldn't figure out. My opinion is that the first move is 1. Re5, but Black still has a variety of moves. Does anyone have better ideas on how to solve it?</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-06-12T14:50:36.863Z
Comments.Text: Users who ask such easily answered questions should just be referred to the source of the answer: https://lichess.org/analysis/8/8/4R3/8/2kBn3/K2pQ3/8/8_w_-_-_0_1
Comments.UserDisplayName: Mobeus Zoom
Tags: <checkmate><problems>
Title: A mate in two problem
ThreadText: # A mate in two problem
  
  (Asked by: username_0 on 2020-12-22)
  
  [FEN "8/8/4R3/8/2kBn3/K2pQ3/8/8 w - - 0 1"]
  
  1. Re5?
  
  With White to move, here is a mate in two problem that I couldn't figure out. My opinion is that the first move is 1. Re5, but Black still has a variety of moves. Does anyone have better ideas on how to solve it?
  
  **Tags:** checkmate, problems
  
  > **Comments:**
  > **username_1**: Users who ask such easily answered questions should just be referred to the source of the answer: https://lichess.org/analysis/8/8/4R3/8/2kBn3/K2pQ3/8/8_w_-_-_0_1  
  
  ---
  
  ## 2 answers
  
  ### Answer by username_3 on 2020-12-22. Score: 7 | Accepted answer
  
  With the rook on e5 to start, there are a number of mates in 2 as discussed. However, with the rook on e6, Bb6 is mate in two. For instance
  
  1. Bb6 d2 2. Qb3 mate
     or 1. ... N any 2. Qc5 mate
     or 1. ... Kc3 2. Qc1
     or 1. ... Kc5 2. Qxd3
     or 1. ... Ke4 2. Qxe4
  
  > **Comments:**
  > **username_4**: Wow lichess doesn’t see it! A plus 1 for you!  
  > **username_1**: @username_4 Yeah, "Lichess" [does](https://lichess.org/analysis/8/8/4R3/8/2kBn3/K2pQ3/8/8_w_-_-_0_1) see it, in the blink of an eye.  
  > **username_4**: @MobeusZoom not on depth 18…  
  > **username_1**: @username_4 Doubt that's possible, depth 18 vs depth 25 makes no difference in spotting a #2. (It only changes eval 19+ moves down the line.)  
  > **username_4**: @MobeusZoom You are lacking a critical understanding in how search depth works. I recommend you peruse an article germane to this subject…  
  
  ---
  
  ### Answer by username_2 on 2020-12-23. Score: 2
  
  I think it is useful in these sorts of problems to categorize moves. You say that Re5 looks promising, but that there are too many moves for black afterwards. I would work through this as follows:
  
  What's good about Re5? It prevents the opponent's king from moving, shrinking the possibilities we need to consider. The threat is 2. Rc5#, but this is prevented by black's knight. If knight moves, 2.Rc5# will be possible because there are no checks. If pawn moves Rc5# remains impossible and no other mate presents itself.
  
  Note that I don't need to consider where the knight is moving *to*. Since we know our threat after Re5 all we have to consider are moves that prevent that threat from working. d2 is such a move, and tells us that Re5 doesn't work.
  
  To find the correct solution, we need to find a different solution to 1... kb5 or kd5. Blocking with the rook of queen like you've proposed doesn't work, so we have to instead look for situations where those moves are mate in 1. This leads us to realize our bishop being in the way is a serious problem, which motivates 1. Bb6, which is indeed correct.
  
  
  ---
  
  