The only reason White would play on the same same side as Black on the 2nd move (rather than on the opposite diagonal) is if she wants a cross game. The decision is up to Black, but there’s is no other reason. I always imagine White thinking "this time I can get a game with diagonal fuseki, it’s now, it’s now…! Oh no, Black played on the same side… oh, it wasn’t this time 
). If White doesn’t want a cross game, the diagonal should always be the rule, taking away Black’s power of choice. Am I missing something here?
There was a decent thread about diagonal fuseki in the past year but I can’t find it. But yes, only if both players want a diagonal opening will it happen. Yes, White is first to signal a desire, and then Black can accept or decline that.
It is sad for lovers of diagonal fuseki, because you don’t get to play it often. When you do, it will be against someone who wants to play it too. That is good, but you can’t use diagonal fuseki skills as a secret weapon to surprise opponents.
2 Likes
Alternatively, if Black opens with an asymmetric move:
Then “the only reason” White would play the diagonally opposite corner is that they don’t care whether Black takes A or B. Right?
For example, I [10k] don’t like Black protecting the weak side of their 3-4 with a stone at A. So I might play at A instead and hope to build a connection across the top kind of like this:
Maybe this one?
4 Likes
I feel like the idea for “cross vs same side” comes mainly from the advantages of having “komi vs first move”
Vague theoretical reasoning
Because black has the first move, thus is always one move ahead in the game, it will be easier for black to build huge territory than it is for white. So black wants to play their first 2 moves on the same side, because then it will be easier to develope something large with those stones.
Of ourse, white does not want black to achieve what black wants to do. For white, white will rather have multiple small territories around the board, so white would generally speaking prefer the cross-opening, because then the likelihood of having multiple small groups will be higher.
If the board has 2 gigantic territories, like ~100 point territory vs another ~100 point territory, komi will be only like less than 5% of the total territory on the board.
But if there’s many small territories, for example total of 10 seperate groups which are all making about 2-10 points worth of territory each, the komi is suddenly worth like 10% of the total territory on the board. Its basically like having one extra living group on the board.
So thats basically the idea why white usually wants to play on the same side as black played: it will leave the possibility of a cross-opening open, while taking away one of the same-side directions from black to develope.
But keep in mind that this is just some extremely deep and vague theoritical meta, it doesnt really matter at all since both options are perfectly good for both players. No game between 2 humans is decided on move 3 xD
Pros often actually choose the cross-opening as black, probably because they feel so confident on their reading skills and fighting abilities, that they are ok with having more complicated game. So i guess that weights more is what the players feel confident with ^^
2 Likes
I found it, it was this Reddit thread
https://www.reddit.com/r/baduk/s/5yGrMQeaaQ
Not really expansive, but I remembered it because Sadaharu explained the idea behind the diagonal fuseki, same as what _KoBa described here.
2 Likes
Nice, I hadn’t thought about that, but that’s only valid if this reason is really important to you and you don’t care about a diagonal opening, or else it’s a gambling. Yeah, thanks for the link, the guy had the same observation as me.
1 Like