Answers.Body: <p>This question led me to spend two hours of my life looking at a line that I most likely never will get to play.  I went into it being quite confident that <code>Nd5</code> was a bad move simply because White would get too much development for the cost of a simple pawn.  Analysing back and forth with Houdini has nevertheless convinced me that <code>Nd5</code> is perfectly playable.</p>
  
  <p><strong>The similarities to the Sokolsky Opening</strong></p>
  
  <p>To get a feel for the <code>b4</code> pawn it helps to understand a variation from <a href="http://en.wikipedia.org/wiki/Sokolsky_Opening" rel="noreferrer">the Sokolsky Opening</a>.  It goes like this:</p>
  
  <pre><code>[FEN ""]
  
  1. b4 e6  2. Bb2 Nf6  3.b5
  </code></pre>
  
  <p>Here the pawn on <code>b5</code> is slightly annoying.  It cannot be easily removed as <code>a6</code> can be answered by <code>a4</code> (it does not matter if the rooks are swapped off as White intends to castle short anyway) and <code>c6</code> can be answered by <code>e3</code> when Black must take away from the centre to remove the pawn.</p>
  
  <p>In the game, however, Black can simply play <code>a6</code> in the similar position as White can't answer with <code>a4</code>:</p>
  
  <pre><code>[FEN ""]
  
  1.f4 Nf6  2. b4 e6  3.b5 a6
  </code></pre>
  
  <p>So after <code>2...e6</code> White is only left with <code>3 a3</code>, which, although reasonable, is another pawn move on the wing.  Black will be very solid after playing simple development like <code>d5</code>, <code>Bd6</code> and <code>0-0</code>.  This is slightly better than one of the main lines of the Sokolsky Opening, which is not that good to start with (but where White often ends up playing <code>f4</code> later).</p>
  
  <p><strong>Houdini 3 on <code>2...Nd5</code></strong></p>
  
  <p>The currently strongest engine on the planet is <a href="http://www.cruxis.com/chess/houdini.htm" rel="noreferrer">Houdini 3</a>.  When you let it analyse the position before <code>2...Nd5</code> to a depth of 25 it likes <code>2...d6</code> (claiming a small advantage for Black) the best (with <code>2...d5</code> as a strong second).  <code>2...Nd5</code> does not come up as a top five alternative.  Houdini is initially not impressed by grabbing the pawn.</p>
  
  <p><strong>White plays <code>3 e4</code></strong></p>
  
  <p>Nevertheless, <code>2...Nd5</code> is still an interesting alternative and certainly gives more entertaining variations to look at.  First let us take a look at what happens if White plays <code>3 e4</code> after <code>2...Nd5</code> and then Black takes the pawn at <code>b4</code>:</p>
  
  <pre><code>[FEN ""]
  
  1.f4 Nf6  2.b4 Nd5  3.e4 Nxb4  4.c3 N4c6  5.d4 d5  6.Nd2 dxe4  7.Nxe4
  </code></pre>
  
  <p>To explain this variation it is important to know that Black's hope and main idea against a setup with f4-e4-d4 is to play <code>d5</code> and develop <code>Bc8</code> to <code>f5</code>or <code>g4</code>.  In the variation above it turns out Black can't play either.  <code>Bg4</code> simply hangs the bishop and <code>Bf5</code> runs into <code>Ng3</code> chasing it back.  Here I (and Houdini) believe White has compensation for the pawn (although perhaps nothing more).</p>
  
  <p>So, let us look at the alternative.  Initially I was sure that <code>3...Nxf4</code> must be horrible for Black, but it turns out it is good after <code>4. d4 e5!</code>:</p>
  
  <pre><code>[FEN ""]
  
  1.f4 Nf6 2.b4 Nd5 3.e4 Nxf4 4.d4 e5 5.dxe5 Ne6
  </code></pre>
  
  <p>As seen above, if White makes the natural capture on e5, Black just retreats the knight.  Material is now even, but Black has two threats; The killing <code>Qh4+</code> and just grabbing the <code>b4</code> pawn.  So Black will end up a pawn up with a much better pawn structure and no imminent attack from White.</p>
  
  <p>Instead White must play:</p>
  
  <pre><code>[FEN ""]
  
  1.f4 Nf6 2.b4 Nd5 3.e4 Nxf4 4.d4 e5 5.Nf3 Ne6 6.d5 Nd4 7.c3 (7.Ng5) Nxf3+ 8.Qxf3 a5
  </code></pre>
  
  <p>In the above variation please note that <code>6 Nxe5</code> runs into <code>6...Qxh4+</code>.  The same idea works against <code>7 Nxd4</code>.  And despite all the knight moves Black is left clearly better in this variation too.  If you want to play this variation with White you need to try the chaotic <code>7.Ng5!?</code>, hoping to trap the knight at d4.  Have fun analysing that.</p>
  
  <p><strong>White plays <code>3 d4</code></strong></p>
  
  <p>I believe <code>3 d4</code> is a strong alternative for White.  If Black takes the pawn on <code>b4</code> it transposes to a variation we have already looked at:</p>
  
  <pre><code>[FEN ""]
  
  1.f4 Nf6 2.b4 Nd5 3.d4 Nxb4 4.c3 N4c6 5.e4 d5 6.Nd2 dxe4 7.Nxe4
  </code></pre>
  
  <p>So, as I mentioned in a comment to the question, perhaps Black can try the amazing <code>3...Nf6</code> with the simple plan of <code>d5</code> and <code>Bf5</code>.  In this variation White will have more space, but also more weaknesses (and, no, Black is not behind in development):</p>
  
  <pre><code>[FEN ""]
  
  1.f4 Nf6 2.b4 Nd5 3.d4 Nf6
  </code></pre>
  
  <p><strong>White plays <code>3 Bb2</code></strong></p>
  
  <p>Seeing that White will lose one pawn anyway, why not play a development move like  and see which pawn Black decides to take?  It seems that Black can just grab the <code>f4</code> pawn and get away with it.  Let us see what happens if White tries to push Black off the board:</p>
  
  <pre><code>[FEN ""]
  
  1.f4 Nf6 2.b4 Nd5 3.Bb2 Nxf4 4.e3 Ng6 5.h4 h5 6.Be2 d5 7.Bxh5 Qd6
  </code></pre>
  
  <p>White won the <code>h5</code> pawn, but now the threat of <code>Qg3+</code> is just killing White.  Instead, if White tried some quiet development moves:</p>
  
  <pre><code>[FEN ""]
  
  1.f4 Nf6 2.b4 Nd5 3.Bb2 Nxf4 4.e3 Ng6 5.Nf3 e5 6.Nxe5 Nxe5 7.Bxe5 Nc6
  </code></pre>
  
  <p>Black gets a small advantage by the precise <code>5...e5</code> which trades the not so optimally placed <code>Ng6</code> (Black is still a pawn up).  Note that the alternative <code>3 Nf3</code> could easily transpose as it does not seem that White can improve much</p>
  
  <p><strong>Conclusion</strong></p>
  
  <p>The fork <code>2...Nd5</code> works out well for Black, despite Houdini's initial reluctance towards it.  It seems White should play <code>3 d4</code> to equalise.  I would certainly try <code>2...Nd5</code> should <code>1 f4 Nf6  2 b4</code> be played against me.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2013-08-03T19:16:31.173Z
Answers.Text: Great, Halvard! This was more than I hoped for. One small question: In the `1.f4 Nf6 2.b4 Nd5 3.d4 Nxb4 4.c3 N4c6` variation, what do you think about `5.d5`?
Answers.UserDisplayName: Dag Oskar Madsen
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2013-08-03T19:32:13.200Z
Answers.Text: I would also add that `1.f4 Nf6 2.b4 Nd5 3.d4 Nxb4 4.a3` looks interesting, with the follow-up `4...Nc6 5.d5 Na5` and later `Bb2`.
Answers.UserDisplayName: Dag Oskar Madsen
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2013-08-03T20:46:48.423Z
Answers.Text: @DagOskarMadsen  This was more than I planned to answer originally :)  Of your two variations I think the `4.a3`-variation feels more natural (as a future `Bb2` just must be good).  It is certainly an interesting alternative to the variation I mentioned.  More chaos, if you like that.
Answers.UserDisplayName: Halvard
Answers.ContentLicense: CC BY-SA 3.0
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Answers.LastActivityDate: 2013-08-03T19:12:43.297Z
Answers.LastEditDate: 2013-08-03T19:12:43.297Z
Answers.UserDisplayName: Halvard
Answers.Body: <p>I think this depends on how you play chess as a human and how good the players are. Some people want to take every pawn they can and then they are defending their king, swapping pieces and then they win the game in the end game. Some want to give them away for some initiative (like white in our example). I think an engine will definitely play <code>Nd5</code> and grab the pawn(s).</p>
  
  <p>I would play <code>Nd5</code> and take <code>b4</code> instead of <code>f4</code>, because white gets aggressive play after <code>e4 Nxf4 d4</code>, especially the half open <code>f</code> file is very nice.</p>
  
  <p>If white plays <code>c3</code> after <code>Nd5</code>, I would take <code>f4</code>.</p>
  
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Answers.LastEditDate: 2019-09-17T16:33:01.970Z
Answers.UserDisplayName: Niklas
Answers.Body: <p>F4 is a reasonable opening move, to discourage Black's e5. He played Nf6 in a similar vein to discourage your e4.</p>
  
  <p>But the followup move, b4, was bad. Not only does it allow the knight fork, but it has no relation to f4. (The fork is really the symptom, and not the disease). Most logically, you might follow with another move on the kingside such as Nf3 or g3. If you want to play on the queen side, the logical moves are Nc3, or d3, both of which would protect a future pawn on e4 from the knight on f6.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-04-24T01:11:26.030Z
Answers.Text: Not entirely true. f4 and b3 are commonly paired to control e5. Playing b4 instead of b3 allows a later b5, controlling c6 where a BN would contest e5. There is at least a little method in the madness.
Answers.UserDisplayName: Philip Roe
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2013-08-03T19:25:04.417Z
Answers.Text: Yes, I agree the `b4` move is a bit random. In the Larsen game it makes more sense, to counter black's fianchetto with a bishop on b2.
Answers.UserDisplayName: Dag Oskar Madsen
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2013-08-03T19:17:36.520Z
Answers.LastActivityDate: 2013-08-03T19:17:36.520Z
Answers.UserDisplayName: Tom Au
Answers.Body: <p>What white is doing doesn't make any sense, it's violating the simple rules of chess: dominating the center.</p>
  
  <p>Nd5 isn't too bad, but the fork is bad i believe</p>
  
  <pre><code>    [FEN ""]
  1.f4 Nf6 2.b4 Nd5 d3 Nxb4 Bd2
  </code></pre>
  
  <p>The knight is lost, if he's gonna retreat, white could start developing his peaces, and black is down in development. </p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2013-08-03T16:57:14.313Z
Answers.Text: -1  For three reasons:  1:  Domination the centre is not a rule, it is more like good practice or a guideline (but I do get your point)  2: `Nd5` ***is*** the fork (meaning if `Nd5`isn't too bad then neither is the fork)  3: The knight is certainly not lost.
Answers.UserDisplayName: Halvard
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2013-08-03T17:30:00.703Z
Answers.Text: @Halvard the knight has to retreat, by doing so, black will give white more advantage, white has 1 move advantage in any game, why give him more and more? if black decided to  defend the knight on d5 square by `a5` then `c3` and now it's lost... lets take another position where black do `c5` instead white respond `c3` i dont think that the black queen could do anything, the knight will be lost if he doesn't retreat as i indicated in my answer, unless you have another line
Answers.UserDisplayName: Lynob
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Answers.Text: The knight is **not** lost.  It can retreat to either `a6` or `c6` without giving White any more tempi for developing.  Even after `4...a5 5.c3` the knight can still retreat to `a6` or to `c6`.  It is not worth giving up the knight for just one tempo.  After `4...N4c6` Black should be perfectly fine (and ready for an imminent `d5`).
Answers.UserDisplayName: Halvard
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Answers.LastActivityDate: 2013-08-03T14:12:10.610Z
Answers.LastEditDate: 2013-08-03T14:12:10.610Z
Answers.UserDisplayName: Lynob
Body: <p>I hope it's OK with a question on the fringes of existing opening theory.</p>
  
  <p>If white wants to combine pawn moves <code>f4</code> and <code>b4</code> early in the opening, he has to be aware of  the possibility of black snatching a pawn. One example is Larsen-Raizman from the 1958 Olympiad <code>1.f4 Nf6 2.Nf3 g6 3.b4</code>, where black could have gone <code>3...Nd5!?</code> with complicated play.</p>
  
  <p>Even earlier possible pawn losses are <code>1.f4 d5 2.b4 Qd6</code> and <code>1.f4 Nf6 2.b4 Nd5</code>. I want to focus on this last variation.</p>
  
  <pre><code>    [FEN ""]
  1.f4 Nf6 2.b4 Nd5
  </code></pre>
  
  <p>Before I thought this was good for black, but now I'm not so sure anymore.
  <code>3.e4 Nxf4 4.d4</code> looks like great compensation, although ironically I would prefer the b4 pawn back on b2. Black is better advised to play <code>3...Nxb4</code>, for instance <code>4.d4 d5</code>. A possible improvement for white is <code>3.d4</code> and after <code>3...Nxb4</code> start chasing the knight around.</p>
  
  <p>Questions:</p>
  
  <p>Is <code>2...Nd5</code> advisable for black?</p>
  
  <p>How should white react?</p>
  
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2013-08-02T17:14:07.007Z
Comments.Text: Once you are into analysing weird variations:  After `1.f4 Nf6 2.b4 Nd5 3.d4` perhaps `3...Nf6` might be playable.  The plan is simply `4...d5` and soon `Bf5` (or `Bg4`).  Talk about flaunting all the rules :)  ( By the way; Hei, Dag!  Lenge siden sist :) )
Comments.UserDisplayName: Halvard
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2013-08-03T19:56:50.360Z
Comments.Text: Speaking of moving the same piece in the opening: I once had a game `1.e4 Nf6 2.e5 Nd5 3.c4 Nb6 4.a4 a5 5.c5 Nd5 6.Nc3 Nb4` with a great position. Five knight moves and `a5`, I wonder if there are any rules for that kind of opening play :)
Comments.UserDisplayName: Dag Oskar Madsen
Tags: <opening><birds-opening>
Title: The earliest possible knight fork
ThreadText: # The earliest possible knight fork
  
  (Asked by: username_0 on 2013-08-01)
  
  I hope it's OK with a question on the fringes of existing opening theory.
  
  If white wants to combine pawn moves `f4` and `b4` early in the opening, he has to be aware of the possibility of black snatching a pawn. One example is Larsen-Raizman from the 1958 Olympiad `1.f4 Nf6 2.Nf3 g6 3.b4`, where black could have gone `3...Nd5!?` with complicated play.
  
  Even earlier possible pawn losses are `1.f4 d5 2.b4 Qd6` and `1.f4 Nf6 2.b4 Nd5`. I want to focus on this last variation.
  
  ```
      [FEN ""]
  1.f4 Nf6 2.b4 Nd5
  
  ```
  
  Before I thought this was good for black, but now I'm not so sure anymore.
  `3.e4 Nxf4 4.d4` looks like great compensation, although ironically I would prefer the b4 pawn back on b2. Black is better advised to play `3...Nxb4`, for instance `4.d4 d5`. A possible improvement for white is `3.d4` and after `3...Nxb4` start chasing the knight around.
  
  Questions:
  
  Is `2...Nd5` advisable for black?
  
  How should white react?
  
  **Tags:** opening, birds-opening
  
  > **Comments:**
  > **username_1**: Once you are into analysing weird variations:  After `1.f4 Nf6 2.b4 Nd5 3.d4` perhaps `3...Nf6` might be playable.  The plan is simply `4...d5` and soon `Bf5` (or `Bg4`).  Talk about flaunting all the rules :)  ( By the way; Hei, Dag!  Lenge siden sist :) )  
  > **username_0**: Speaking of moving the same piece in the opening: I once had a game `1.e4 Nf6 2.e5 Nd5 3.c4 Nb6 4.a4 a5 5.c5 Nd5 6.Nc3 Nb4` with a great position. Five knight moves and `a5`, I wonder if there are any rules for that kind of opening play :)  
  
  ---
  
  ## 4 answers
  
  ### Answer by username_1 on 2013-08-03. Score: 6 | Accepted answer
  
  This question led me to spend two hours of my life looking at a line that I most likely never will get to play. I went into it being quite confident that `Nd5` was a bad move simply because White would get too much development for the cost of a simple pawn. Analysing back and forth with Houdini has nevertheless convinced me that `Nd5` is perfectly playable.
  
  **The similarities to the Sokolsky Opening**
  
  To get a feel for the `b4` pawn it helps to understand a variation from [the Sokolsky Opening](http://en.wikipedia.org/wiki/Sokolsky_Opening). It goes like this:
  
  ```
  [FEN ""]
  
  1. b4 e6  2. Bb2 Nf6  3.b5
  
  ```
  
  Here the pawn on `b5` is slightly annoying. It cannot be easily removed as `a6` can be answered by `a4` (it does not matter if the rooks are swapped off as White intends to castle short anyway) and `c6` can be answered by `e3` when Black must take away from the centre to remove the pawn.
  
  In the game, however, Black can simply play `a6` in the similar position as White can't answer with `a4`:
  
  ```
  [FEN ""]
  
  1.f4 Nf6  2. b4 e6  3.b5 a6
  
  ```
  
  So after `2...e6` White is only left with `3 a3`, which, although reasonable, is another pawn move on the wing. Black will be very solid after playing simple development like `d5`, `Bd6` and `0-0`. This is slightly better than one of the main lines of the Sokolsky Opening, which is not that good to start with (but where White often ends up playing `f4` later).
  
  **Houdini 3 on `2...Nd5`**
  
  The currently strongest engine on the planet is [Houdini 3](http://www.cruxis.com/chess/houdini.htm). When you let it analyse the position before `2...Nd5` to a depth of 25 it likes `2...d6` (claiming a small advantage for Black) the best (with `2...d5` as a strong second). `2...Nd5` does not come up as a top five alternative. Houdini is initially not impressed by grabbing the pawn.
  
  **White plays `3 e4`**
  
  Nevertheless, `2...Nd5` is still an interesting alternative and certainly gives more entertaining variations to look at. First let us take a look at what happens if White plays `3 e4` after `2...Nd5` and then Black takes the pawn at `b4`:
  
  ```
  [FEN ""]
  
  1.f4 Nf6  2.b4 Nd5  3.e4 Nxb4  4.c3 N4c6  5.d4 d5  6.Nd2 dxe4  7.Nxe4
  
  ```
  
  To explain this variation it is important to know that Black's hope and main idea against a setup with f4-e4-d4 is to play `d5` and develop `Bc8` to `f5`or `g4`. In the variation above it turns out Black can't play either. `Bg4` simply hangs the bishop and `Bf5` runs into `Ng3` chasing it back. Here I (and Houdini) believe White has compensation for the pawn (although perhaps nothing more).
  
  So, let us look at the alternative. Initially I was sure that `3...Nxf4` must be horrible for Black, but it turns out it is good after `4. d4 e5!`:
  
  ```
  [FEN ""]
  
  1.f4 Nf6 2.b4 Nd5 3.e4 Nxf4 4.d4 e5 5.dxe5 Ne6
  
  ```
  
  As seen above, if White makes the natural capture on e5, Black just retreats the knight. Material is now even, but Black has two threats; The killing `Qh4+` and just grabbing the `b4` pawn. So Black will end up a pawn up with a much better pawn structure and no imminent attack from White.
  
  Instead White must play:
  
  ```
  [FEN ""]
  
  1.f4 Nf6 2.b4 Nd5 3.e4 Nxf4 4.d4 e5 5.Nf3 Ne6 6.d5 Nd4 7.c3 (7.Ng5) Nxf3+ 8.Qxf3 a5
  
  ```
  
  In the above variation please note that `6 Nxe5` runs into `6...Qxh4+`. The same idea works against `7 Nxd4`. And despite all the knight moves Black is left clearly better in this variation too. If you want to play this variation with White you need to try the chaotic `7.Ng5!?`, hoping to trap the knight at d4. Have fun analysing that.
  
  **White plays `3 d4`**
  
  I believe `3 d4` is a strong alternative for White. If Black takes the pawn on `b4` it transposes to a variation we have already looked at:
  
  ```
  [FEN ""]
  
  1.f4 Nf6 2.b4 Nd5 3.d4 Nxb4 4.c3 N4c6 5.e4 d5 6.Nd2 dxe4 7.Nxe4
  
  ```
  
  So, as I mentioned in a comment to the question, perhaps Black can try the amazing `3...Nf6` with the simple plan of `d5` and `Bf5`. In this variation White will have more space, but also more weaknesses (and, no, Black is not behind in development):
  
  ```
  [FEN ""]
  
  1.f4 Nf6 2.b4 Nd5 3.d4 Nf6
  
  ```
  
  **White plays `3 Bb2`**
  
  Seeing that White will lose one pawn anyway, why not play a development move like and see which pawn Black decides to take? It seems that Black can just grab the `f4` pawn and get away with it. Let us see what happens if White tries to push Black off the board:
  
  ```
  [FEN ""]
  
  1.f4 Nf6 2.b4 Nd5 3.Bb2 Nxf4 4.e3 Ng6 5.h4 h5 6.Be2 d5 7.Bxh5 Qd6
  
  ```
  
  White won the `h5` pawn, but now the threat of `Qg3+` is just killing White. Instead, if White tried some quiet development moves:
  
  ```
  [FEN ""]
  
  1.f4 Nf6 2.b4 Nd5 3.Bb2 Nxf4 4.e3 Ng6 5.Nf3 e5 6.Nxe5 Nxe5 7.Bxe5 Nc6
  
  ```
  
  Black gets a small advantage by the precise `5...e5` which trades the not so optimally placed `Ng6` (Black is still a pawn up). Note that the alternative `3 Nf3` could easily transpose as it does not seem that White can improve much
  
  **Conclusion**
  
  The fork `2...Nd5` works out well for Black, despite Houdini's initial reluctance towards it. It seems White should play `3 d4` to equalise. I would certainly try `2...Nd5` should `1 f4 Nf6 2 b4` be played against me.
  
  > **Comments:**
  > **username_0**: Great, username_1! This was more than I hoped for. One small question: In the `1.f4 Nf6 2.b4 Nd5 3.d4 Nxb4 4.c3 N4c6` variation, what do you think about `5.d5`?  
  > **username_0**: I would also add that `1.f4 Nf6 2.b4 Nd5 3.d4 Nxb4 4.a3` looks interesting, with the follow-up `4...Nc6 5.d5 Na5` and later `Bb2`.  
  > **username_1**: @username_0  This was more than I planned to answer originally :)  Of your two variations I think the `4.a3`-variation feels more natural (as a future `Bb2` just must be good).  It is certainly an interesting alternative to the variation I mentioned.  More chaos, if you like that.  
  
  ---
  
  ### Answer by username_2 on 2013-08-01. Score: 2
  
  I think this depends on how you play chess as a human and how good the players are. Some people want to take every pawn they can and then they are defending their king, swapping pieces and then they win the game in the end game. Some want to give them away for some initiative (like white in our example). I think an engine will definitely play `Nd5` and grab the pawn(s).
  
  I would play `Nd5` and take `b4` instead of `f4`, because white gets aggressive play after `e4 Nxf4 d4`, especially the half open `f` file is very nice.
  
  If white plays `c3` after `Nd5`, I would take `f4`.
  
  
  ---
  
  ### Answer by username_3 on 2013-08-03. Score: 1
  
  F4 is a reasonable opening move, to discourage Black's e5. He played Nf6 in a similar vein to discourage your e4.
  
  But the followup move, b4, was bad. Not only does it allow the knight fork, but it has no relation to f4. (The fork is really the symptom, and not the disease). Most logically, you might follow with another move on the kingside such as Nf3 or g3. If you want to play on the queen side, the logical moves are Nc3, or d3, both of which would protect a future pawn on e4 from the knight on f6.
  
  > **Comments:**
  > **username_0**: Yes, I agree the `b4` move is a bit random. In the Larsen game it makes more sense, to counter black's fianchetto with a bishop on b2.  
  > **username_4**: Not entirely true. f4 and b3 are commonly paired to control e5. Playing b4 instead of b3 allows a later b5, controlling c6 where a BN would contest e5. There is at least a little method in the madness.  
  
  ---
  
  ### Answer by username_5 on 2013-08-03. Score: 0
  
  What white is doing doesn't make any sense, it's violating the simple rules of chess: dominating the center.
  
  Nd5 isn't too bad, but the fork is bad i believe
  
  ```
      [FEN ""]
  1.f4 Nf6 2.b4 Nd5 d3 Nxb4 Bd2
  
  ```
  
  The knight is lost, if he's gonna retreat, white could start developing his peaces, and black is down in development.
  
  > **Comments:**
  > **username_1**: -1  For three reasons:  1:  Domination the centre is not a rule, it is more like good practice or a guideline (but I do get your point)  2: `Nd5` ***is*** the fork (meaning if `Nd5`isn't too bad then neither is the fork)  3: The knight is certainly not lost.  
  > **username_5**: @username_1 the knight has to retreat, by doing so, black will give white more advantage, white has 1 move advantage in any game, why give him more and more? if black decided to  defend the knight on d5 square by `a5` then `c3` and now it's lost... lets take another position where black do `c5` instead white respond `c3` i dont think that the black queen could do anything, the knight will be lost if he doesn't retreat as i indicated in my answer, unless you have another line  
  > **username_1**: The knight is **not** lost.  It can retreat to either `a6` or `c6` without giving White any more tempi for developing.  Even after `4...a5 5.c3` the knight can still retreat to `a6` or to `c6`.  It is not worth giving up the knight for just one tempo.  After `4...N4c6` Black should be perfectly fine (and ready for an imminent `d5`).  
  
  ---
  
  