Life In 19x19

kokomi wrote:

Bill Spight wrote:

kokomi wrote:why gote is preferred to reverse sente?

In general, to get the last play at the level of the plays,

For instance, suppose that the last two plays are a gote that gains 1 point and a reverses sente that gains 1 point. If you take the reverse sente, you gain 1 point, but then the opponent takes the gote to gain 1 point, as well. Net result: 0. But if you take the gote, you gain 1 point, and then the opponent takes his sente, for no gain. Net result: 1 point for you. Note that in the second line of play you get the last play (the reply to the sente).

ok, this sounds reasonable. When i have a rs of 2pts and a gote of 1pt, so i should go rs first. Then it's like when the pts of rs=gote, gote is preferred to rs?

Yes, in general. But be aware of miai.

RedStick wrote:Bill and Topaz, you guys make my head hurt.

You're welcome.

bill:
can you give me a simple diagram of reverse sente vs gote?
i can not understand why gote is prefered.

Okay, I think I mostly understand this, finally? I had never seen game trees before, and was about to ask, but decided it would be polite to research the basics first. Those are here: http://senseis.xmp.net/?MiaiCountingWithTrees. So if I'm not mistaken, the left leaf is black filling, totalling zero points there. The branch at B is if black takes 'c' on the board? White takes so, black gets either -1 or -3 points, depending on if black captures back. Is this a correct interpretation of the tree you drew?

Thanks to both sides, this discussion is educational.

I think it is because the evaluation of a reverse sente move is effectively 2 * what it would be if it was gote. So an RS move that technically looks like 3 points is the equivalent of 6 points gote, and in that case you'd play a 6 move gote typically before a 3 point reverse sente... Blah, this stuff is crazy on definitions alone

Magicwand wrote:bill:
can you give me a simple diagram of reverse sente vs gote?
i can not understand why gote is prefered.

Ah, Magic Man!

See #17 in this thread: http://www.lifein19x19.com/forum/viewto ... 9605#p9605

I tried understanding combinatorial game theory from the Sensei's Library pages and was left utterly confused. Then I downloaded some of the Berlekamp and Spight papers (because the were free) and was still very confused. Finally I checked out Mathematical Go from the library, and was slightly less confused. Finally I also checked out Winning Ways, and between the two of them I think I finally have a pretty good handle on the stuff Bill's talking about. If you're curious, here's my advice:

1) go to http://cgsuite.sourceforge.net/ and download cgsuite. You can play around with examples and be amazed when it tells you {2|1||1|-3}=1 and such.

2) get Winning Ways and Mathematical Go. Mathematical go should be all you need, but Winning Ways explains slowly and in more detail summing games, reversing moves, and so on.

edit: also for what it's worth I found Berlekamp's decision to chill all the positions more confusing than helpful. You don't need to change {1|-1} to {0|0} I think.

Chew Terr wrote:Okay, I think I mostly understand this, finally? I had never seen game trees before, and was about to ask, but decided it would be polite to research the basics first. Those are here: http://senseis.xmp.net/?MiaiCountingWithTrees. So if I'm not mistaken, the left leaf is black filling, totalling zero points there. The branch at B is if black takes 'c' on the board? White takes so, black gets either -1 or -3 points, depending on if black captures back. Is this a correct interpretation of the tree you drew?

Thanks to both sides, this discussion is educational.

"The branch at B is if black takes 'c' on the board?"

No, all the play is on the top side, in the area around "a".

Sorry. I'll change the lettering in the tree.

i never used formula to calculate the values.
but it looks intresting.

i know for fact that there are 9 dans who doesnt know such formula and are strong at endgame.
i believe the experience and intuation alone will be enough to compare the value of 2 different endgame.
although it is intresting i think people need to learn to feel the end game first.

in my opinion the formula confuses me more and take longer to calculate.

So the left branch is if white lets black fill?

The right branch is if white captures. The left branch is if black gets the next local play (capturing back to -1 points) and the right is if white gets to connect.

Now am I correctly interpreting the tree?

Bill Spight wrote:

Magicwand wrote:bill:
can you give me a simple diagram of reverse sente vs gote?
i can not understand why gote is prefered.

Ah, Magic Man!

See #17 in this thread: http://www.lifein19x19.com/forum/viewto ... 9605#p9605

thank you for your info.
but that is an example of 2 point gote vs 1 point RS.
if it was equal valued point then RS is always bigger. (excluding miai)

Magicwand wrote:i never used formula to calculate the values.
but it looks intresting.

i know for fact that there are 9 dans who doesnt know such formula and are strong at endgame.
i believe the experience and intuation alone will be enough to compare the value of 2 different endgame.
although it is intresting i think people need to learn to feel the end game first.

in my opinion the formula confuses me more and take longer to calculate.

There is a famous game where Shusai took 8 hours (!) to work out the endgame. In the 19th century endgame errors (not counting minor inaccuracies) among top players were extremely rare. In the 20th century, with quicker games (one or two days), even top players made mistakes in the middle endgame, with occasional mistakes even later.

Endgame texts are full of errors. I remember playing out one of Sakata's games when a play came up that the books showed as sente, but I had worked out was really gote. Did Sakata play it as sente? Nope.

Chew Terr wrote:So the left branch is if white lets black fill?

The right branch is if white captures. The left branch is if black gets the next local play (capturing back to -1 points) and the right is if white gets to connect.

Now am I correctly interpreting the tree?

Yes. A left branch indicates a Black play, a right branch indicates a White plays.

Thanks, that was the key I was missing =)

Magicwand wrote:

Bill Spight wrote:

Magicwand wrote:bill:
can you give me a simple diagram of reverse sente vs gote?
i can not understand why gote is prefered.

Ah, Magic Man!

See #17 in this thread: http://www.lifein19x19.com/forum/viewto ... 9605#p9605

thank you for your info.
but that is an example of 2 point gote vs 1 point RS.
if it was equal valued point then RS is always bigger. (excluding miai)

Remember the rule to double the size of the RS to compare it with the gote. They are equal in size.

Several posts in this thread have addressed that.