MNb wrote on 03/25/11 at 00:49:55:


I tend to agree.

The Marshall Gambit in the Ruy Lopez is a good example of a gambit that works equally well in blitz and classical games. I guess this is the result of the Marshall becoming very theoretical and fashionable.

It's hard to say whether the Anti-Moscow is a better practical option in blitz or classical chess. One slack move can cause a lot of problems for White, but the same applies for Black. No wonder the Anti-Moscow Gambit is very trendy. 

There is also the complicating factor that if a gambit is well-known or popular such as the the Smith-Morra Gambit, it might be harder to gain an advantage even in blitz.

I don't think general statements like these make much sense. Some gambits are completely sound. One modern example is the Anti-Moscow Gambit.
The only valid general statement is this one. If a gambit offers a theoretical advantage to the gambit player it will not occur in superGM games, because nobody will want to defend it. If a gambit is unsound or dubious it will not occur in superGM games either, because nobody will want to risk it. If a gambit for White is too drawish it will not occur in superGM games, unless they are happy with a draw. If a gambit for Black is sound superGM's will test its soundness now and then.
So only the unclear gambits remain - like that Anti-Moscow Gambit. Once the overall verdict becomes more or less clear (the Najdorf PP, the Perenyi Gambit) it inevitably loses its popularity.

> could this also mean that time control can be a factor when evaluating the position

this is more a factor for evaluating players' ability. No wonder that gambits work well in quick games, when initiative and time gained on the clock make wonders. on ICC it is not unusual to see gambiteers winning on time with two pieces less. What surprises me, though, is that on computer-guys sites (e.g. rybkaforum), some players with very strong hardware consider that e.g. the Morra gambit is not "winning" (in practical terms) for Black against equal-strength opposition. It would be interesting to have the dispassionate views of such people, if such thing is possible.

> Also, there might be gambits where the gambiteer has not sacrificed for attacking chances but for more positional reasons?

Benko & Budapest gambit spring to mind, as well as lines of the 9.0-0-0 Dragon where Black plays for the draw with one pawn less. From White's point of view, it's harder to find gambits that doesnn't convert into attacking chances, since White already starts with a lead in devt and initiative. There are some White positional gambits in the English or the Catalan, to induce pawn weaknesses, but there are more of middlegame type. Another motivation for gambitting with White is to avoid theory, e.g. with 1.d4 Nf6 2.g4.

It also happens that White must gambit as a least worst option in the course of an opening. Consider for instance 1.c4 e5 and here 2.Nf3, assuming White doesn't fancy 2.Nc3 Bb4 nor 2.g3 Nf6 3.Bg2 c6. Play may continue 2...e4 3.Nxd4 Nc6, and if White doesn't play the lame 4.Nxc6 (tried several times by Murey to no avail), he must go for 4.e3 Nd4 5.exd4 Qf6. Now 6.d5 Bc5 is a disaster, so at this point White's best is to gambit with 6.Nc3 Qxd4 7. Be2 followed with 0-0 and d3, with typical method Nb5 at some stage. It takes some nerves to gambit a central pawn in the English, but this is White's best chance in this line (this gambit was recommended by Watson, but I don't know if anybody actually tried it). So here White gambits a pawn in order to avoid the unpromising (in his view) ...Bb4 and Keres lines. A responsable tradeoff!

Sometimes in wide open positions like after a gambit, good-looking attacks aren't hard to find while a correct defence may require a bit of effort, one slip and it can be all over for the defender. However attack isn't always easier than defence. Sometimes defending is very easy while trying to attack it is very difficult.    
  
It's true that sacrifices need less justification in shorter time limits, this is pretty well known. But good work finding this out for yourself TC.

I have got an idea about positional evaluation of certain sharp gambits that I can not get out of my mind.

The idea is that certain gambits can better for the gambiteer in blitz games, slightly better for the extra material in standard time games and winning for extra material in correspondence games. Could this theory actually be true?

I got this idea while examing the From gambit where I analysed a game from local club between who other players when I took the moves from memory since that game was never published in any way (and lower rated gambiteer won).