Answers.Body: <p>The objective is <em>not</em> to eliminate the rooks.</p>
  <p>The objective is to <strong>remove black's defense of the <code>e8</code> square</strong> so that <code>Qe8#</code> can be played.</p>
  <p>After <code>Nxd8</code>, does black still control <code>e8</code>?</p>
  
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Answers.Text: Or, the goal is to eliminate the book *from the action*. Eliminating them from the board is in service of that, not the ultimate goal in itself.
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Answers.Text: @Acccumulation and Mateen Ulhaq perhaps this should be on meta, but can't OP just plug this into a computer? i guess a computer doesn't answer everything, but i think it's still in that range in like how maths se would consider like insufficient effort (i don't want to say low effort though!). i think OP should've plugged into computer and then could ask questions about what computer says. otherwise this page will be flooded with 'trivial' (see round bracket remark next!) puzzles like these (trivial in the sense that it's easily answered by computers, not that it's necessarily easy to answer)
Answers.UserDisplayName: BCLC
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Answers.Text: @BCLC That might be worth posting on meta. There's a large number of questions posted here that can be answered with an engine. That seems to be accepted, so it seems people see value in a human-to-human exchange rather just an engine answer. For instance, in this case, answers consist of not just giving the answer to taking with the knight, but discussion of larger principles.
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Answers.UserDisplayName: Mateen Ulhaq
Answers.Body: <p>White wants to play Qe8 for a back rank mate (since the Black king has no escape square).  To do so, he must eliminate Black's protection of the e8 square. Capturing both rooks accomplishes that by 1. Rxd8+, Rxd8 2. Rxd8+ Rxd8 3. Qe8 mate. But if he plays 1..., Nxd8 instead of 1..., Rxd8, he interrupts the other Black rook's protection of the e8 square, and White is able to mate a move sooner by 2. Qe8 mate.</p>
  
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Answers.UserDisplayName: CConero
Answers.Body: <blockquote>
  <p>However, if black takes with Rook, then Knight takes' white's rook,
  white rook to take knight, then black rook to take white rook. This
  prevents the Qe8 mate, doesn't it?</p>
  </blockquote>
  <p>No, it accelerates it. Let's look at what happens if black takes with the knight instead of the rook</p>
  <pre><code>[fen &quot;1r1r2k1/6pp/2n4q/2p1p2Q/pp2N2P/5P2/PPPR2P1/1K1R4 w - - 0 1&quot;]
  
  1. Rxd8 Nxd8 2. Qe8# {oops!}
  </code></pre>
  <p>Black gets checkmated in 2 moves instead of 3</p>
  
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Answers.CreationDate: 2021-01-15T20:59:45.500Z
Answers.Text: Ah! Thanks, don't know how I didn't see that. I bet that's the "proper" answer too, instead of wasting the extra moves the other way.
Answers.UserDisplayName: BruceWayne
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Answers.Text: @BruceWayne: black tries to delay mate, even if it is unavoidable.
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Answers.Text: @RazvanSocol and Brian Towers♦ perhaps this should be on meta, but can't OP just plug this into a computer? i guess a computer doesn't answer everything, but i think it's still in that range in like how maths se would consider like insufficient effort (i don't want to say low effort though!). i think OP should've plugged into computer and then could ask questions about what computer says. otherwise this page will be flooded with 'trivial' (see round bracket remark next!) puzzles like these (trivial in the sense that it's easily answered by computers, not that it's necessarily easy to answer)
Answers.UserDisplayName: BCLC
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Answers.UserDisplayName: Brian Towers
Body: <p>I am working through <em>Bobby Fischer Teaches Chess</em> and #134 asks</p>
  <blockquote>
  <p>If White plays Rook-takes-Rook-check, can he mate?</p>
  </blockquote>
  <p>The answer is Yes, the mate is delivered by the white Queen.  However, can't it be prevented?</p>
  <p>Here's the board:</p>
  <pre><code>[title &quot;Bobby Fischer #134&quot;]
  [fen &quot;1r1r2k1/6pp/2n4q/2p1p2Q/pp2N2P/5P2/PPPR2P1/1K1R4 w - - 0 1&quot;]
  </code></pre>
  <p>I can see how to get mate, with the Queen: 1. Rxd8 Rxd8 2. Rxd8 Nxd8 3. Qe8  for mate.</p>
  <p>However, if 1. Rxd8 Nxd8 2. Rxd8 Rxd8 .  This <em>prevents</em> the Qe8 mate, doesn't it?</p>
  <p>So when the question asks &quot;can he mate&quot;, yes but it's not guaranteed.  Do I understand the board correctly?</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-01-18T10:33:23.623Z
Comments.Text: Suggestion: If Bobby gives it as an example it "must" be doable. He would not have intended it not to be guaranteed one or other way.  Given that, trying very long and hard to see how it can be will probably help you more long term than asking the fine folks here - no matter how painful the quest may be. [[FWIW - my ability at chess is abysmal - consider doing what I say - not what I'd do :-) !!!}.
Comments.UserDisplayName: Russell McMahon
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-01-18T13:36:42.103Z
Comments.Text: I wonder what move black previously made to get the board to that position... its seems highly unlikely that white queen is just sitting there for the taking, but black did something else instead.
Comments.UserDisplayName: musefan
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-01-18T13:59:37.600Z
Comments.Text: perhaps this should be on meta, but can't OP just plug this into a computer? i guess a computer doesn't answer everything, but i think it's still in that range in like how maths se would consider like insufficient effort (i don't want to say low effort though!). i think OP should've plugged into computer and then could ask questions about what computer says. otherwise this page will be flooded with 'trivial' (see round bracket remark next!) puzzles like these (trivial in the sense that it's easily answered by computers, not that it's necessarily easy to answer)
Comments.UserDisplayName: BCLC
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-01-18T15:06:11.770Z
Comments.Text: @BCLC can you outline how to do that? I'm just starting to learn chess and would appreciate any info on that!
Comments.UserDisplayName: BruceWayne
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-01-18T15:08:52.387Z
Comments.Text: @RussellMcMahon agree 100%, I did stare at it and think for a while... But it was after reading the book straight for like an hour so should have probably just taken a break and come back with fresh eyes :)
Comments.UserDisplayName: BruceWayne
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-01-18T15:09:59.403Z
Comments.Text: @musefan I would guess that black's last move was Qh6, presumably moving off of f6 to avoid capture from the knight.  (d6 is also possible, but I doubt she'd be in a position to be attacked by both knight and rook at the same time.)  Black can't take the white queen because every subsequent move after that is a check that has to be dealt with.
Comments.UserDisplayName: Darrel Hoffman
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-01-19T09:46:01.233Z
Comments.Text: @DarrelHoffman: Yeah I would have assumed so too. Still seems strange though as if black is offering up a queen trade then they must realise the immediate danger, which makes it less likely for them to move. Anyway, I assume it wasn't a real game, but it's fun to wonder non the less...
Comments.UserDisplayName: musefan
Tags: <checkmate><study>
Title: How is mate guaranteed - Bobby Fischer 134
ThreadText: # How is mate guaranteed - Bobby Fischer 134
  
  (Asked by: username_0 on 2021-01-15)
  
  I am working through *Bobby Fischer Teaches Chess* and #134 asks
  
  > If White plays Rook-takes-Rook-check, can he mate?
  
  The answer is Yes, the mate is delivered by the white Queen. However, can't it be prevented?
  
  Here's the board:
  
  ```
  [title "Bobby Fischer #134"]
  [fen "1r1r2k1/6pp/2n4q/2p1p2Q/pp2N2P/5P2/PPPR2P1/1K1R4 w - - 0 1"]
  
  ```
  
  I can see how to get mate, with the Queen: 1. Rxd8 Rxd8 2. Rxd8 Nxd8 3. Qe8 for mate.
  
  However, if 1. Rxd8 Nxd8 2. Rxd8 Rxd8 . This *prevents* the Qe8 mate, doesn't it?
  
  So when the question asks "can he mate", yes but it's not guaranteed. Do I understand the board correctly?
  
  **Tags:** checkmate, study
  
  > **Comments:**
  > **username_1**: Suggestion: If Bobby gives it as an example it "must" be doable. He would not have intended it not to be guaranteed one or other way.  Given that, trying very long and hard to see how it can be will probably help you more long term than asking the fine folks here - no matter how painful the quest may be. [[FWIW - my ability at chess is abysmal - consider doing what I say - not what I'd do :-) !!!}.  
  > **username_2**: I wonder what move black previously made to get the board to that position... its seems highly unlikely that white queen is just sitting there for the taking, but black did something else instead.  
  > **username_3**: perhaps this should be on meta, but can't OP just plug this into a computer? i guess a computer doesn't answer everything, but i think it's still in that range in like how maths se would consider like insufficient effort (i don't want to say low effort though!). i think OP should've plugged into computer and then could ask questions about what computer says. otherwise this page will be flooded with 'trivial' (see round bracket remark next!) puzzles like these (trivial in the sense that it's easily answered by computers, not that it's necessarily easy to answer)  
  > **username_0**: @username_3 can you outline how to do that? I'm just starting to learn chess and would appreciate any info on that!  
  > **username_0**: @username_1 agree 100%, I did stare at it and think for a while... But it was after reading the book straight for like an hour so should have probably just taken a break and come back with fresh eyes :)  
  > **username_4**: @username_2 I would guess that black's last move was Qh6, presumably moving off of f6 to avoid capture from the knight.  (d6 is also possible, but I doubt she'd be in a position to be attacked by both knight and rook at the same time.)  Black can't take the white queen because every subsequent move after that is a check that has to be dealt with.  
  > **username_2**: @username_4: Yeah I would have assumed so too. Still seems strange though as if black is offering up a queen trade then they must realise the immediate danger, which makes it less likely for them to move. Anyway, I assume it wasn't a real game, but it's fun to wonder non the less...  
  
  ---
  
  ## 3 answers
  
  ### Answer by username_8 on 2021-01-15. Score: 25 | Accepted answer
  
  > However, if black takes with Rook, then Knight takes' white's rook,
  > white rook to take knight, then black rook to take white rook. This
  > prevents the Qe8 mate, doesn't it?
  
  No, it accelerates it. Let's look at what happens if black takes with the knight instead of the rook
  
  ```
  [fen "1r1r2k1/6pp/2n4q/2p1p2Q/pp2N2P/5P2/PPPR2P1/1K1R4 w - - 0 1"]
  
  1. Rxd8 Nxd8 2. Qe8# {oops!}
  
  ```
  
  Black gets checkmated in 2 moves instead of 3
  
  > **Comments:**
  > **username_0**: Ah! Thanks, don't know how I didn't see that. I bet that's the "proper" answer too, instead of wasting the extra moves the other way.  
  > **username_9**: @username_0: black tries to delay mate, even if it is unavoidable.  
  > **username_3**: @username_9 and username_8 username_8♦ perhaps this should be on meta, but can't OP just plug this into a computer? i guess a computer doesn't answer everything, but i think it's still in that range in like how maths se would consider like insufficient effort (i don't want to say low effort though!). i think OP should've plugged into computer and then could ask questions about what computer says. otherwise this page will be flooded with 'trivial' (see round bracket remark next!) puzzles like these (trivial in the sense that it's easily answered by computers, not that it's necessarily easy to answer)  
  
  ---
  
  ### Answer by username_5 on 2021-01-16. Score: 17
  
  The objective is *not* to eliminate the rooks.
  
  The objective is to **remove black's defense of the `e8` square** so that `Qe8#` can be played.
  
  After `Nxd8`, does black still control `e8`?
  
  > **Comments:**
  > **username_6**: Or, the goal is to eliminate the book *from the action*. Eliminating them from the board is in service of that, not the ultimate goal in itself.  
  > **username_3**: @username_6 and username_5 username_5 perhaps this should be on meta, but can't OP just plug this into a computer? i guess a computer doesn't answer everything, but i think it's still in that range in like how maths se would consider like insufficient effort (i don't want to say low effort though!). i think OP should've plugged into computer and then could ask questions about what computer says. otherwise this page will be flooded with 'trivial' (see round bracket remark next!) puzzles like these (trivial in the sense that it's easily answered by computers, not that it's necessarily easy to answer)  
  > **username_6**: @username_3 That might be worth posting on meta. There's a large number of questions posted here that can be answered with an engine. That seems to be accepted, so it seems people see value in a human-to-human exchange rather just an engine answer. For instance, in this case, answers consist of not just giving the answer to taking with the knight, but discussion of larger principles.  
  
  ---
  
  ### Answer by username_7 on 2021-01-16. Score: 4
  
  White wants to play Qe8 for a back rank mate (since the Black king has no escape square). To do so, he must eliminate Black's protection of the e8 square. Capturing both rooks accomplishes that by 1. Rxd8+, Rxd8 2. Rxd8+ Rxd8 3. Qe8 mate. But if he plays 1..., Nxd8 instead of 1..., Rxd8, he interrupts the other Black rook's protection of the e8 square, and White is able to mate a move sooner by 2. Qe8 mate.
  
  
  ---
  
  