## Chess!

Of the Tabletop, and other, lesser varieties.

Moderators: SecondTalon, Moderators General, Prelates

LaserGuy
Posts: 4576
Joined: Thu Jan 15, 2009 5:33 pm UTC

### Re: Chess!

KnightExemplar wrote:I made a mistake with my analysis earlier. My previous post makes no damn sense.

Spoiler:
King is very dead with 2. Rf1.

1. ... Rc3 2. Rf1, B(Harry Potter)c5. 3. Q tries to block, Harry Potter takes Queen, ggs.

Spoiler:
No, because you can block with Rf2 instead. If the bishop captures the rook, you can escape to Kf1.

Also note:

Spoiler:
Ron is threatening checkmate himself with Nh3. The queen is trapped on the 3rd rank to prevent Ron from checkmating the king.

Spoiler:
Qf5 defends against that move. You can just move the king since Hermione isn't covering f1 or f2 anymore.

KnightExemplar
Posts: 5494
Joined: Sun Dec 26, 2010 1:58 pm UTC

### Re: Chess!

LaserGuy wrote:
KnightExemplar wrote:I made a mistake with my analysis earlier. My previous post makes no damn sense.

Spoiler:
King is very dead with 2. Rf1.

1. ... Rc3 2. Rf1, B(Harry Potter)c5. 3. Q tries to block, Harry Potter takes Queen, ggs.

Spoiler:
No, because you can block with Rf2 instead. If the bishop captures the rook, you can escape to Kf1.

Ah Chess, the combinations are ever extensive! For this particular path... it still leads to checkmate.

Spoiler:
1. ... Rc3 2. Rf1, B(Harry Potter)c5. 3. Rf2 (block the Bishop), Rc1 checkmate

In this case, Harry Potter doesn't deliver the checkmate, but its still a checkmate.

Also note:

Spoiler:
Ron is threatening checkmate himself with Nh3. The queen is trapped on the 3rd rank to prevent Ron from checkmating the king.

Spoiler:
Qf5 defends against that move. You can just move the king since Hermione isn't covering f1 or f2 anymore.

Hmmm, okay, I think I'm just gonna post my analysis from SCID vs PC later. I don't think I'm a good enough Chess player to see all the possibilities without computer assistance.
First Strike +1/+1 and Indestructible.

LaserGuy
Posts: 4576
Joined: Thu Jan 15, 2009 5:33 pm UTC

### Re: Chess!

KnightExemplar wrote:
Spoiler:
1. ... Rc3 2. Rf1, B(Harry Potter)c5. 3. Rf2 (block the Bishop), Rc1 checkmate

In this case, Harry Potter doesn't deliver the checkmate, but its still a checkmate.

Spoiler:
Well, you can still block Qf1, but then Ron gets the mate with Nh3, I think. Kind of sexy.

I'd be interested in seeing the analysis of this position. As I said, because of the free move at the start for White, I feel like there's a lot of variations that you'd need to check.
Spoiler:
2. Rc3 Nf3 or even 2. Rc3 h6 look plausible

KnightExemplar
Posts: 5494
Joined: Sun Dec 26, 2010 1:58 pm UTC

### Re: Chess!

LaserGuy wrote:I'd be interested in seeing the analysis of this position. As I said, because of the free move at the start for White

The Puzzle states explicitly "Black to Move", so Black actually has the first move.

Anyway, Stockfish has found that the optimal play is in fact the path you were talking about.

Spoiler:
Checkmate in 11.

1...Rc3 2.Qf5 Rxf5 3.Nxf5 Rc2 4.Nh4 Be4 5.Nd5 Nh3+ 6.Kf1 Bd3+ 7.Ke1 Re2+ 8.Kf1 Nc4 9.Ng6+ hxg6 10.Rd1 Bb4 11.Rxd3 Rf2#

This is a Queen sacrifice to keep the game going on, but it makes Black give up Hermione. I commanded Stockfish to look for the 2nd best variation (hopefully one to not lose Hermione), and it still sacrifices Hermione (the Rook)

Stockfish only declares "Checkmate" if it is impossible to avoid, so that's the optimal moves. Not quite what the original Youtube Video said, so I guess the puzzle is a little bit flawed. Still, it seems like a "reasonable position" that satisfies all of the drama needed for the film.
First Strike +1/+1 and Indestructible.

Aiwendil
Posts: 313
Joined: Thu Apr 07, 2011 8:53 pm UTC
Contact:

### Re: Chess!

Spoiler:
Doesn't the puzzle require that Ron sacrifice himself? Maybe I've missed it, but I don't see the Ron sacrifice in any of the solutions discussed above.

LaserGuy
Posts: 4576
Joined: Thu Jan 15, 2009 5:33 pm UTC

### Re: Chess!

Google's Deep Mind Alpha just obliterated Stockfish in a 100 game series, with Deep Mind winning 28, drawing 72 and losing none. Apparently Google gave its algorithm 4 hours of training time prior to the match.

Carlington
Posts: 1588
Joined: Sun Mar 22, 2009 8:46 am UTC
Location: Sydney, Australia.

### Re: Chess!

ChessNetwork on Youtube has been doing analyses of the ten games that were made public.

Also, as long as I'm here, I'd like to share a screenshot of what horrible despair looks like:

Spoiler:
Kewangji: Posdy zwei tosdy osdy oady. Bork bork bork, hoppity syphilis bork.

Eebster the Great: What specifically is moving faster than light in these examples?
doogly: Hands waving furiously.

Please use he/him/his pronouns when referring to me.