user3387: After White's 22. Bc1, it seems like responding with Rd2 would keep the game alive for Black. I assume Friedel's a more insightful player than I am. What am I missing? That is, from an experienced player's viewpoint, why do we assume that staying alive with Rd2 is not worth the effort, and how would White be sure to win regardless?
[fen ""]
[White "Nakamura"]
[Black "Friedel"]
[Event "US Championship 2009"]

1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 d5 5. exd5 Na5 6. Bb5 c6 7. dxc6 bxc6 8. Bd3 Be7 9. Nc3 O-O 10. O-O Rb8 11. h3 c5 12. b3 Rb4 13. Re1 Bb7 14. Ba3 Rf4 15. g3 Rd4 16. Nf3 Rd3 17. cxd3 Qd3 18. Ne5 Qf5 19. g4 Qf4 20. d4 Rd8 21. Qe2 Rd4 22. Bc1


user12540: Rd2 (giggling) is just a move like a computer which will not lose until it has been programmed to resign. There is nothing Black can do except run like a mouse here & there. White is in an extreme dominating position with his Beautiful Knight on e5 making him supreme in the Game. Question is after sacrificing the rook what black can do?
The point of this game is the exchange sacrifice on 16th move Rd3 which does not seem to be correct because white sacrificed his pawns and did not keep his weaknesses intact. He just opened up the position and Black made a tactical mistake and White trapped the queen. 
Thanks for bringing this game into concern . A lot of things to learn here .

user3270: "That is, from an experienced player's viewpoint, why do we assume that staying alive with Rd2 is not worth the effort, and how would White be sure to win regardless?"
I don't want to speak for you but it seems you're getting more at a philosophical question about whether or not to resign than asking about the position.
For an under 1200 section, this position may well be playable. As you get better, though, there are two factors which make you resign more frequently.
The first is that the amount of energy you expend when playing chess goes up as your ability increases. It is very draining to play a slow game as a strong player, particularly when you have a bad position and it may be affecting your mood. In a tournament like the US Championship, the expected points you gain from the time to rest and prepare for your next game following a quick resignation dwarfs the expectation from dragging out a dead lost game. This ties into the second reason:
Anybody decent, and especially not (in 2009) world top-20 GM Hikaru Nakamura, is going to let you get away with anything more than a loss in this position. Black staked everything on an attack which white easily rejected and won a ton of material besides. Playing this game out is just going to make people dislike you.

user2042: 
After White's 22. Bc1, it seems like responding with Rd2 would keep the game alive for Black. 

This is an entirely wrong assumption. Black has no counterplay whatsoever, while White holds the initiative. Being down material, Black has no resources/time to repel the coming attack, nor to organize a defense/counterplay. Because his queen is trapped he will be forced to lose even more material, which will only make things easier for White.

I assume Friedel's a more insightful player than I am. What am I missing? 

[Title "Easiest way to win this position as White"]
[StartFlipped "0"]
[fen "6k1/pb2bppp/5n2/n1p1N3/3r1qP1/1PN4P/P3QP2/R1B1R1K1 b - - 0 1"]

1...Rd2 $8 2.Bxd2 Qb4 $8 3.Nd5! $18 Qa3 ( 3...Qd4 4.Nxe7+ $18 ) 4.Nxe7+ $18

With two rooks up, White has an easy task of continuing the mating attack.

That is, from an experienced player's viewpoint, why do we assume that staying alive with Rd2 is not worth the effort, and how would White be sure to win regardless?

He probably saw the line from the above diagram and decided to resign. Even though you are an inexperienced player, I doubt you would lose that position against the strongest engine on Earth, since Black has no counterplay and will be forced to exchange pieces to prolong the game after which extra rooks will decide. I will give you just one sample line that shows how I would continue as White:
[Title "Easiest way to win this position as White"]
[StartFlipped "0"]
[fen "6k1/pb2bppp/5n2/n1p1N3/3r1qP1/1PN4P/P3QP2/R1B1R1K1 b - - 0 1"]

1...Rd2 $8 2.Bxd2 Qb4 $8 3.Nd5! $18 Qa3 ( 3...Qd4 4.Nxe7+ $18 ) 4.Nxe7+ Kf8 $8 ( 4...Kh8 5.Nxf7# ) 5.Nd7+ Ke8 ( 5...Nxd7 6.Ng6+ Kg8 ( 6...fxg6 7.Qe8# ) ( 6...hxg6 7.Qe8# ) 7.Qe8+ Nf8 8.Qxf8# ) 6.Nxf6+ gxf6 ( 6...Kd8 7.Bxa5+ Qxa5 8.Qd3+ Kc7 9.Qg3+ Kb6 ( 9...Kd8 10.Qd6# ) 10.Qd6+ Kb5 ( 10...Bc6 11.Qxc6# ) 11.a4+ Kb4 ( 11...Qxa4 12.bxa4+ Kb4 ( 12...Ka5 13.Qxc5+ Ka6 14.Qb5# ) 13.Qd2+ Kc4 ( 13...Kb3 14.Re3+ Kc4 15.Qc3# ) 14.Rec1+ Kb3 15.Qc3# ) 12.Qd2+ Kxb3 13.Qd3+ Qc3 ( 13...Kb2 14.Reb1# ) ( 13...Kb4 14.Reb1# ) 14.Reb1# ) ( 6...Kf8 7.Ng6+ fxg6 ( 7...hxg6 8.Qe8# ) 8.Qe8# ) 7.Nd5+ Kd7 ( 7...Kd8 8.Qe8# ) ( 7...Kf8 8.Bh6+ Kg8 9.Qe8# ) 8.Qe8+ Kd6 9.Bf4+ Kxd5 10.Qe4#

As you can see, although the number of lines is vast, the attack is straightforward. The only "problem" I had with analyzing this for White was to find the best check with the queen so I can keep the lines forcing. I had to spend half an hour calculating all the lines but am sure a player of Nakamura's strength would find these in a matter of seconds...
The above lines very instructively illustrate the hopelessness of Black's position, so there is no need for me to add anything else. If you need further help or clarification leave a comment. 
Best regards.

user2800: 22...Rd2 saves the queen, but black is still down a massive amount of material. After white takes the rook on d2, he has two rooks for just a bishop. With such a huge material deficit, there is no possible hope of defending with normal play. The only chance for black would be to have an immediate attack on the king or other very strong compensation, which is not the case in the game. White's king is slightly open, but black has no way to take advantage of it and white can easily cover any threats to his king. Since black has no meaningful way to generate any play to make up for the material, he resigned.

3387: <p>After White's 22. Bc1, it seems like responding with Rd2 would keep the game alive for Black. I assume Friedel's a more insightful player than I am. What am I missing? That is, from an experienced player's viewpoint, why do we assume that staying alive with Rd2 is not worth the effort, and how would White be sure to win regardless?</p>

<pre><code>[fen ""]
[White "Nakamura"]
[Black "Friedel"]
[Event "US Championship 2009"]

1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 d5 5. exd5 Na5 6. Bb5 c6 7. dxc6 bxc6 8. Bd3 Be7 9. Nc3 O-O 10. O-O Rb8 11. h3 c5 12. b3 Rb4 13. Re1 Bb7 14. Ba3 Rf4 15. g3 Rd4 16. Nf3 Rd3 17. cxd3 Qd3 18. Ne5 Qf5 19. g4 Qf4 20. d4 Rd8 21. Qe2 Rd4 22. Bc1
</code></pre>
 12540: <p>Rd2 (giggling) is just a move like a computer which will not lose until it has been programmed to resign. There is nothing Black can do except run like a mouse here &amp; there. White is in an extreme dominating position with his Beautiful Knight on e5 making him supreme in the Game. Question is after sacrificing the rook what black can do?</p>

<p>The point of this game is the exchange sacrifice on 16th move Rd3 which does not seem to be correct because white sacrificed his pawns and did not keep his weaknesses intact. He just opened up the position and Black made a tactical mistake and White trapped the queen. </p>

<p>Thanks for bringing this game into concern . A lot of things to learn here .</p>
 3270: <p>"That is, from an experienced player's viewpoint, why do we assume that staying alive with Rd2 is not worth the effort, and how would White be sure to win regardless?"</p>

<p>I don't want to speak for you but it seems you're getting more at a philosophical question about whether or not to resign than asking about the position.</p>

<p>For an under 1200 section, this position may well be playable. As you get better, though, there are two factors which make you resign more frequently.</p>

<p>The first is that the amount of energy you expend when playing chess goes up as your ability increases. It is very draining to play a slow game as a strong player, particularly when you have a bad position and it may be affecting your mood. In a tournament like the US Championship, the expected points you gain from the time to rest and prepare for your next game following a quick resignation dwarfs the expectation from dragging out a dead lost game. This ties into the second reason:</p>

<p>Anybody decent, and especially not (in 2009) world top-20 GM Hikaru Nakamura, is going to let you get away with anything more than a loss in this position. Black staked everything on an attack which white easily rejected and won a ton of material besides. Playing this game out is just going to make people dislike you.</p>
 2042: <blockquote>
  <p>After White's 22. Bc1, it seems like responding with Rd2 would keep the game alive for Black. </p>
</blockquote>

<p>This is an entirely wrong assumption. Black has no counterplay whatsoever, while White holds the initiative. Being down material, Black has no resources/time to repel the coming attack, nor to organize a defense/counterplay. Because his queen is trapped he will be forced to lose even more material, which will only make things easier for White.</p>

<blockquote>
  <p>I assume Friedel's a more insightful player than I am. What am I missing? </p>
</blockquote>

<pre><code>[Title "Easiest way to win this position as White"]
[StartFlipped "0"]
[fen "6k1/pb2bppp/5n2/n1p1N3/3r1qP1/1PN4P/P3QP2/R1B1R1K1 b - - 0 1"]

1...Rd2 $8 2.Bxd2 Qb4 $8 3.Nd5! $18 Qa3 ( 3...Qd4 4.Nxe7+ $18 ) 4.Nxe7+ $18
</code></pre>

<p>With two rooks up, White has an easy task of continuing the mating attack.</p>

<blockquote>
  <p>That is, from an experienced player's viewpoint, why do we assume that staying alive with Rd2 is not worth the effort, and how would White be sure to win regardless?</p>
</blockquote>

<p>He probably saw the line from the above diagram and decided to resign. Even though you are an inexperienced player, I doubt you would lose that position against the strongest engine on Earth, since Black has no counterplay and will be forced to exchange pieces to prolong the game after which extra rooks will decide. I will give you just one sample line that shows how I would continue as White:</p>

<pre><code>[Title "Easiest way to win this position as White"]
[StartFlipped "0"]
[fen "6k1/pb2bppp/5n2/n1p1N3/3r1qP1/1PN4P/P3QP2/R1B1R1K1 b - - 0 1"]

1...Rd2 $8 2.Bxd2 Qb4 $8 3.Nd5! $18 Qa3 ( 3...Qd4 4.Nxe7+ $18 ) 4.Nxe7+ Kf8 $8 ( 4...Kh8 5.Nxf7# ) 5.Nd7+ Ke8 ( 5...Nxd7 6.Ng6+ Kg8 ( 6...fxg6 7.Qe8# ) ( 6...hxg6 7.Qe8# ) 7.Qe8+ Nf8 8.Qxf8# ) 6.Nxf6+ gxf6 ( 6...Kd8 7.Bxa5+ Qxa5 8.Qd3+ Kc7 9.Qg3+ Kb6 ( 9...Kd8 10.Qd6# ) 10.Qd6+ Kb5 ( 10...Bc6 11.Qxc6# ) 11.a4+ Kb4 ( 11...Qxa4 12.bxa4+ Kb4 ( 12...Ka5 13.Qxc5+ Ka6 14.Qb5# ) 13.Qd2+ Kc4 ( 13...Kb3 14.Re3+ Kc4 15.Qc3# ) 14.Rec1+ Kb3 15.Qc3# ) 12.Qd2+ Kxb3 13.Qd3+ Qc3 ( 13...Kb2 14.Reb1# ) ( 13...Kb4 14.Reb1# ) 14.Reb1# ) ( 6...Kf8 7.Ng6+ fxg6 ( 7...hxg6 8.Qe8# ) 8.Qe8# ) 7.Nd5+ Kd7 ( 7...Kd8 8.Qe8# ) ( 7...Kf8 8.Bh6+ Kg8 9.Qe8# ) 8.Qe8+ Kd6 9.Bf4+ Kxd5 10.Qe4#
</code></pre>

<p>As you can see, although the number of lines is vast, the attack is straightforward. The only "problem" I had with analyzing this for White was to find <strong>the best check with the queen</strong> so I can keep the lines forcing. I had to spend half an hour calculating all the lines but am sure a player of <em>Nakamura's</em> strength would find these in a matter of seconds...</p>

<p>The above lines very instructively illustrate the hopelessness of Black's position, so there is no need for me to add anything else. If you need further help or clarification leave a comment. </p>

<p>Best regards.</p>
 2800: <p>22...Rd2 saves the queen, but black is still down a massive amount of material. After white takes the rook on d2, he has two rooks for just a bishop. With such a huge material deficit, there is no possible hope of defending with normal play. The only chance for black would be to have an immediate attack on the king or other very strong compensation, which is not the case in the game. White's king is slightly open, but black has no way to take advantage of it and white can easily cover any threats to his king. Since black has no meaningful way to generate any play to make up for the material, he resigned.</p>
