4.e3 is something I've referred to as the Slow Slav (4...Bf5 or 4...Bg4, while 4...e6 could transpose to a Semi-Slav). 
Useful post!
Do you have any up-to-date recommendations on the, Meran? As White, I'm especially concerned with this move order, e.g, 1 d4, d5; 2 c4, e6; 3 Nc3, c6; 4 Nf3, Nf6; 5 e3

fluffy wrote on 08/05/10 at 20:39:23:

Thx, fluffy, I fully agree with you and your replies #8 and #19 (the latter was your answer to a post of mine where I was slightly confused about sth. I'd like to explain.)

Today: 
I agree, today we refer to the Semi-Slav as everything that touches the position after 1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Nc3 e6 (or is classified by ECO-Codes D43-D49 which is just the same)

Historically (in the 20th century):
however, things were somewhat different, as chess theory mainly focused on the QDG and not the Slav. So quite a number of definitions were different from today. -- Euwe 1966 or BCO2 (Kasparow/Keene 1992) defined the Semi-Slav by the position that is reached after 
1. d4 d5 2. c4 e6 3. Nc3 c6

This has a number of consequences. For these 20th century authors, Noteboom or Marshall Gambit 4.e4 used to be discussed under the Semi-Slav lines! 

What is more, the name Moscow variation was used in 20th century (e.g. Taimanow 1980) for the line 
1. d4 d5 2. c4 e6 3. Nf3 Nf6 4. Bg5 h6 while today we take it for granted that Moscow variation means the position after 
1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Nc3 e6 5. Bg5 h6 6. Bxf6 (whereas 6.Bh4 is called the Anti Moscow line).

Summing up, all I want to point out is that there is historically quite some confusion about these definition. And off-hand I can't think of any other terretory of opening theory that has undergone a similar development and shift of focus and names.

Looking at these developments. Is anyone able to explain who was driving these changes (in the definition of the Semi-Slav) and when exactly this happened? I just gave samples from a few books I own and this does not allow me to make too precise conclusions, I'm afraid.

It's hard to believe this thread has gone on so long, but I thought I'd jump in with my own attempt at reconciliation (for the sake of Knightmare, mostly).

After 1.d4 d5 2.c4 c6, the opening is a Slav Defense.  From here, the game will turn into a Semi-Slav if: 

1) Black plays ...e6 before ...dxc4, or
2) Black eschews the chance to develop his LSB outside the pawn chain and plays ...e6 with the d-pawn still on d5.

Off the top of my head, that should clear things up and leave the Geller Gambit in the Slav proper.  Or did I just muddy the waters even more?

Note that I'm ignoring transpositions to the QGD, for instance, because they must go "through" the Semi-Slav and I name an opening variation based on the position reached, not the move order to get there.  Thus, 1.d4 d5 2.c4 c6 starts as a Slav, 3.Nf3 Nf6 4.Nc3 e6 changes to a Semi-Slav, and 5.Bg5 Nbd7 6.e3 finally transposes to a QGD.

H-HH wrote on 08/04/10 at 16:32:37:


Well, nice answer. Everything that refutes the definition is an exception, if I understand you. And around the Slav / Semi-Slav there are many.
But still the definition is correct? Extremely convincing, really.

The simple answer to the basic question what the definition of the Slav or the Semi-Slav (or basically any opening) is, is where the given position is listed in ECO. 
An example of the weaknesses of that System (and there are many) is the Geller-Gambit. Or the Vienna-Variation in the QGD to give another example. There simply is no "inner logic" in that System.

Anonymous3 wrote on 06/26/10 at 04:02:24:


Well, sorry, you both are wrong. Which is proven by the main line of the Geller-Gambit.

Though I like to add that trw is even wronger, as I do not think that there is a single line of the Semi-Slav with pawns on e6 and c6, where the bishop is outside the pawn chain. 

fluffy wrote on 06/29/10 at 13:27:05:


I couldn't disagree with any of these words.

If you have arrived at useful definitions, then just let me know what you think about this one: 1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Nc3 dxc4 5. a4 e6 *
A Slav or rather a Semi-Slav?

The situation isn't getting any easier when you look at the moves to come:

A) 6. e3 c5 7. Bxc4 Nc6 8. O-O cxd4 9. exd4 Be7 *
This looks very much like a QGA. However, the system of encyclopaedia of chess openings ECO stills classifies this as a Slav position (D16). The difference to a true QGA is minuscule. Here is pawn is on a7, while in the QGA after 1. d4 d5 2. c4 dxc4 3. Nf3 Nf6 4. e3 e6 5. Bxc4 c5 6. O-O a6 7. a4 Nc6 8. Nc3 cxd4 9. exd4 Be7 * Black has the pawn on a6.

B) 6. e4 Bb4 7. e5 Ne4 *
There are some famous Alekhine games vs. Euwe and vs. Bogoljubow with this line (and this move order). And yet this line gets an ECO classification of D31 (aka Semi-Slav) because the very same position can also arise from a Semi-Slav move order 1. d4 d5 2. c4 e6 3. Nc3 c6 4. Nf3 dxc4 5. a4 Bb4 6. e4 (?) Nf6 (?) 7. e5 Ne4 *
Some books or DVDs (e.g. Euwe 1966 or Shirov 2010) still preferred to discuss this line in their Slav sections. BTW, Euwe argues that in this Semi-Slav move order 6. e4 is weak because of the stronger reply 6... b5!

Tricky, isn't it?

That's a preciser way to formulate it; of course I would not propose to give two move orders that lead to the same position a different name.

fluffy wrote on 06/28/10 at 23:34:19:

You can't get it more precise, except that should be added "from 2...c6 on". But that's what you meant of course.

MNb wrote on 06/28/10 at 21:32:35:


well, they are of course. ECO is based on moves, not prose. for some people it helps to verbalize. It's actually a pretty good system, excpet for some lack of flexibility (D85 and B90 being prominent examples). In any case, the Semi-Slav only encompasses positions normally reached after 1.d4 d5 2.c4 e6 3.Nf3 Nf6 4.Nc3 e6. Anything up to but not including 4...e6 can be constituted as a Slav. One must always be wary of transpositions, for example starting with the Semi-Slav position, 5.Bg5 Nbd7 is considered a QGD, as ECO deems it 'more natural' to have this position arise from 1.d4 d5 2.c4 e6.

hmm.

"At any rate nothing you've said, breaks my argument only his. His argument was it can only be considered a slav with Bf5 or Bg4 (outside the chain) and my argument was purely thats not a necessary distinction."

straw man. that is not what anonymous3 said. he said in the Slav Black generally tries to develop the bishop outside the pawn chain, which is true. I looked again at the original thread and to me it's very obvious that trw does not understand the distinction at all. It does not matter what Shirov said - I doubt he cares much about the semantics.

philisophically, Black is trying to develop the c8-bishop, so he plays ...c6. Of course White can do some things to force Black to alter his plans (3.cxd5; 3.Nc3 Nf6 4.e3). In the main position 1.d4 d5 2.c4 e6 3.Nf3 Nf6 4.Nc3 Black must give up the centre in order to develop this bishop, as 4...Bf5?! runs into 5.cxd5 cxd5 6.Qb3. Playing the Semi-Slav with 4...e6 (the defining move) is quite different. Here Black clearly is not developing the bishop outside the pawn chain. Rather, he is 'threatening' to take on c4 and thus hoping to force White to play 5.e3 himself, which would lock in the c1-bishop. Often White plays the sharp 5.Bg5, but this comes at a price, either after the pawn grab (sack!?) 5...dxc4 or the bishop grab 5...h6, which as we know in modern practice is often met by the sacrifice 6.Bh4!?

Don't let pride get in the way of acquiring knowledge.

trw, you are so wrong! 

The reason that you won't tell me what books you have that recommend 4...e6 after 1 d4 d5 2 c4 c6 3 Nf3 Nf6 4 g3 is because their aren't any!

trw, your comment "If you wanted a real poll you would ask the question if 1. d4 d5 c4 c6 Nf3 Nf6 Nc3 dxc4 was considered a Slav. If people said yes then i'm right. If they say no, you are right" is totally wrong. We both agree that after 1 d4 d5 2 c4 c6 3 Nf3 Nf6 4 Nc3, 4...dxc4 is a Slav. I never said it wasn't. I said the Slav is generally where you try to develop the bishop outside the pawn chain. I never said that you have to develop the bishop outside the pawnchain for it to be a Slav. The main idea behind 4...dxc4 is to be try and develop the bishop to f5 safely without worrying about Qb3. That is why 4...dxc4 is considered to be a Slav, even if White prevents ...Bf5 with something like e4. We also agree that blocking in the bishop with 4...e6 after something like 1 d4 d5 2 c4 c6 3 Nf3 Nf6 4 Nc3, is the Semi-Slav. What we disagree on is if Black develops his bishop outside the pawn chain after something like 1 d4 d5 2 c4 c6 3 Nf3 Nf6 4 g3 Bf5. You say it is a Semi-Slav but I (and just about everyone else) say it's a Slav. I am afraid you are wrong on this trw!

Actually, Fluffy's comment just breaks your argument trw. After 1 d4 d5 2 c4 c6 3 Nf3 Nf6 4 e3, 4...Bf5 or 4...Bg4 is called the Slow Slav. It's not a Semi-Slav like you say it is.  

Also trw, I didn't wrongly sum up your argument. I just basically restated what you wrote in one of your poss in the thread  "Slav Question" and here it is: "Slav is with c6 dxc4. Semi-slav is with e6 c6 (Bishop placement irrelevant)."

this is a funny thread. 

"In  any case, I know i'm right"

sounds convincing to me!

"and i'll quote directly from ECO"

well, ECO considers D10-D19 the Slav, and D43-49 the Semi-Slav. Some other transpositions are possible, for example 1.d4 d5 2.c4 e6 3.Nf3 Nf6 4.Qc2 dxc4 5.Qxc4 is a Queen's Gambit Accepted (D21, if memory serves).

The Slav is not only 4...dxc4 now, is it? There is something called the Exchange Slav (D13-14), while 4.e3 is something I've referred to as the Slow Slav (4...Bf5 or 4...Bg4, while 4...e6 could transpose to a Semi-Slav). 4...dxc4 could be called the Slav "Accepted" or even the "Main Line Slav" D15 begins coverage of 4...dxc4, and D16 is the start of 5.a4.

4...a6 is the Chebanenko or ...a6 Slav. 4...g6 is the Schlecter Slav (which ECO classifies as a Grunfeld), although Black usually avoids this unless White has commited to an early e2-e3.
And then there is 4...e6, the Semi-Slav! D43 is the Moscow Variation and other early deviations, while D44 is the Botvinnik Variation. D45-D49 covers 5.e3 - the Meran and friends.

Hopefully this shed some light to all on the ECO classification. If not, that's ok, because I know I'm right.

Hmm, right now the vote is 12-1 in my favor and I'm assuming the only person who voted for trw is trw! 

I'll repeat what I said under the post "Slav Question" with a few additions:

I said the Slav is generally where you develop the bishop outside of the pawn structure. It's basically the lines where you are trying to develop the bishop outside of the pawn structure. After 1 d4 d5 2 c4 c6 3 Nf3 Nf6 4 Nc3 dxc4 (basically the main point behind this move is develop the bishop to f5 and not be worried about Qb3, this is why it's considered to be a Slav even if White prevents Black from developing the bishop outside the pawn structure) 5 e4 (The Slav Geller Gambit, which isn't thought to be that good for White) White doesn't allow you to develop the bishop outside of the pawnchain safely so in this case you won't have the bishop developed outside of the pawn structure. 

I'm still waiting for those 15+ books that you have that recommend 4...e6 after 1 d4 d5 2 c4 c6 3 Nf3 Nf6 4 g3.

trw wrote on 06/27/10 at 22:32:33:


Hmm, it might well be the case that newish lines such as the a6 Slav have blurred the boundaries (and that is clearly what Shirov was alluding to), but the distinction made in the posts by Anonymous3 and myself is the traditional one and the one generally understood and recognized by strong players and Slav/Semi-Slav experts everywhere. All the serious books on the topic that I am aware of back this up as well. 

You are free to believe what you like, of course, but the evidence is against you, sorry.

Anonymous3 wrote on 06/26/10 at 04:02:24:


There is really no room for argument. 

Anonymous3 is correct in saying:
"I ("Anonymous3") say that the Semi-Slav is where you play ...c6 and block in the bishop with ...e6 and the Slav is where you play ...c6 and generally develop the bishop outside the pawn chain. (cut)"

But both Slav and Semi-Slav often involve Black taking on c4.

Also it can be hard for novices to appreciate the differences between the Semi-Slav and the Orthodox. Basically in the Semi-Slav Black plays ...e6 (as in the Orthodox) but the main point is that he plays ...c6 much earlier than in the Orthodox in order to threaten to take on c4 and then either hang on to the pawn on c4 by ...b5 or else gain a tempo for queenside expansion and the development of the queen's bishop to b7 by ...b5, after white recaptures on c4 with his bishop (usually) or queen.

The Semi-Slav move order basically presents White with two major choices: either gambit the c4 pawn for centre control and initiative (Botvinnik and Moscow systems) or defend the c4 pawn but allow Black a sort of souped-up Queen's Gambit Accepted with White's queen's knight already committed to c3 (Meran).

Under the post Slav Question, me ("Anonymous3") and "trw" have been in an argument on what is the difference between the Slav and Semi-Slav. 

I ("Anonymous3") say that the Semi-Slav is where you play ...c6 and block in the bishop with ...e6 and the Slav is where you play ...c6 and generally develop the bishop outside the pawn chain. The Slav can involve ...dxc4.

"trw" says that the Semi-Slav is where you play both ...c6 and ...e6 but it doesn't matter if the bishop is developed outside of the pawnchain or not and the Slav is where you play ...c6 and ...dxc4. 

Vote for who you think is correct.