Old Benoni without D5

how does black play if white does not respond with 2. d5 after 1. d4 c5?  For instance what does black do if white goes with e3 or c3.

If e3, take and enjoy your central pawn majority. If c3, develop naturally (Nf6, e6, Be7, O-O) and play a game of chess

is cxd4 really the best line against e3? what are the main continuations after that?

I don't know that there are any main continuations. Is e3 played a lot?  Just get your pieces out, get castled and roll with the punches.

After cxd4 exd4 Black has the better structure in the long run and still has the flexibility to adopt any setup he wants. 3.Qxd4 Nc6 takes on the character of a Qxd4 open sicilian with Whites pawn not yet on e4

Or if you're comfortable playing a Caro-Kann, 3...d5 (after 3.exd4) is an exchange variation.

ok I see why cxd4 works, but the thing is I took up old benoni to play for a win with black against lower rated players...(I use semi slav against people equal or higher than myself)  and if we are transposing to exchange slav or panov botvinnik its hard to win with black..  Okay exchange slav I have some lines, but i can't seem to find anything satisfactory with panov botvinnik.  Any suggestions for how to play for a win with blackside of panov?

I doubt that taking immediately is the best idea. Playable for sure, but the panov-botwinnik against the caro is far from toothless. Trasposing to a challenging mainline of an entirely different opening might be labeled as a failure for black who has stepped on unfamiliar and dangerous ground (of course black is ok in this variation but only if he knows his stuff). It might be a good idea only if you play the caro against e4. I would instead play 2...Nf6, 2...e6 or 2...d5 (probably the first one makes more sense for an old benoni player). Then it's white to move and only after he shows his plan you can decide whether it's a good idea to take (for example if he has played a move which wouldn't be good in a panov-botwinnik setup). With 2.e3 white gives you the control of the central tension and momentarily blocks his bishop. Why should you hurry in solving that tension and freeing that bishop? instead wait for white to make a concession, and strike at the right moment!

The way I see it, after cxd4 exd4, Black's pawn isn't already on d5 as in the CK exhange so he's not obliged to transpose to a Panov. He can go ahead with his development and leave White guessing as to what central structure he's going to adopt.

A central pawn majority is a nice thing to have. It was Bent Larsen who once famously called 3.d4 in the Sicilian a positional blunder

yes, but an open e-file is also a good thing...and also a queenside majority in an endgame, it's not like the resulting structure is strictly better for one side: one(black) has the minority attack and central majority and the other(white) has more important open lines and definitely the greater piece activity (counterquote  Tarrasch  said"i don't care about the pawn structure as long as the pieces are active"). It's a balanced situation. Of course cxd4 immediately is 100% ok.

But it's also clear that black is in no rush (surely white isn't going to get anything by playing dxc5) so why playing that immediately instead of wayting for white to make a concession?

Of course, you're right there's nothing wrong with waiting either, although I wouldn't wait too long or White just might try to take himself and hold on to the pawn.

A matter of taste I suppose. I just like the fact that Black hasn't comitted to playing d5 yet. Whites central pawn isn't easy to defend either.

I prefer to take and say to White "you're going to regret that" 

And I think the half open e-file is more of an illusion than a real advantage, while the c-file is a very real one (if White plays c6 he has to worry about the minority attack)

It's basically a Carlsbad structure with some (maybe not so) subtle differences

White is never going to regret giving black the possibility of forcing him in a perfectly ok structure. In itself it's not advantageus for white or black; white has definitely the better piece activity while black has in theory the possibility of a minority attack. The resulting positions are not easy for black to handle; the panov was considered a very serious try far an advantage for decades (today is not considered white best i think, but still i know that a lot of caro players fear it), and i don't think not having played d5 yet gives black better alternatives. d6 + g6 doesn't look like making particular sense against a possible c3-d4 barrier. In fact i looked at a database and the vast majority of games trasposed to the panow-botwinnik with 3...d5, with a considerable plus score for white (an old benoni player is unlikely to be at ease in the very open waters of this variation).

i don't get the remark about white central pawn being hard to defend (only in his dreams black can put the slightest pressure on d4). Also white is never going to take and hold the pawn. 

A basic positional principle is than the side which controls the tension should not release it without a concrete gain. after 2.e3 Nf6 black has total control of the tension, since dxc5 is almost always going to be bad(in the sense of very unambitious, of course white is not worse) for white (unless he plays something like a3 intending dxc5-b4, but this would be easily meet with an immediate cxd4 laughting at white lost tempo). So 2...cxd4 is 100% playable but also a sort of slight positional mistake. The only way to make white regret e3 is not taking immediately and generating this "i'll take on d4 whenever i want and you can only wait and see or admit that i'm easily equal by taking yourself" where play is balanced but black is the one dictating the pace of the game.

The only reason to prefer 2...cxd4 is that you're a caro player and so trasposing is 100% ok for you. 2...Nf6 or 2...e6 are more logical for everyone else, more played and score better than 2...cxd4 on all the databases i looked at. I don't think it's 100% a matter of tastes, 2...cxd4 is objectively slighly(very sligtly) inferior to the alternatives. Black of course equalizes in both cases, the difference is that with 2...cxd4 he has to prove he is equal and will manage to do so if he knows his theory around move 15 , while with 2...Nf6 he can probably be defined already equal.

I am fine with transposing to panov botvinnik, but the line I play is a more or less forced ending line in which black can't really play for a win...so yes 2. nf6 is probably more logical.  But if anyone knows any lines where black can go into the panov and play for a win, i'm open to suggestions.

The whole point of the Panov is pressure on the d5 pawn, trying to force Black to take on c4 and retaking with gain of tempo (or taking on d5 himself with Black  using a piece to recapture) and trying to take advantage of the isolated q-pawn position. Without the pawn on d5, where's the pressure?

Of course Black can pressure White's center, the c4-d4 pawn duo won't be able to comfortably advance, while if White plays c3 to strongpoint d4 then (whether or not Black lands a pawn on d5 first) a typical QGD minority attack is in the air.

A central pawn majority is a concrete positional gain. I don't know that White has gained anything more substantial than some open lines of development (we should also remember that it's Black to move), this isn't an open Sicilian where White is going to blow Black away with f4 and e5/f5. His half open e-file is nothing more than a conduit to the kingside and his queenside majority is going to look like swiss cheese by the time Black gets done with it.

Each to his own, if you want to keep the tension then keep the tension but no matter what the engines say (small plus for White) personally I would take Black every time after cxd4 exd4

redchessman, I would say if you want to play for the win, study typical QGD structures from the White side

Ok, it's (mainly) a matter of tastes and your tastes are clear . 

But no matter what engines say, after cxd4 exd4 it's an undeniable truth that white side is preferable(but black can of course equalize with correct play). I suggest you to study the position is more depth, because is not really possible to think that black is preferable here after having looked at some lines. We are in an ancient mainline which has been played by several world champions, if you think that you would rather take black clearly either you or Botwinnik are wrong. 

A central pawn majority is indeed a concrete gain, but also white much greater piece mobility is a concrete gain. By the way you should also forget about the minority attack. A minority attack is never going to happen once white has played c4, we are in a completely different structure. White non-existent queenside majority (soon or later the c4 and d5 pawn are going to be exchanged, so it's a+b pawn vs a+b pawn, where's the majority?) is never going to be "reduced to swiss cheese" by black non-existent queenside minority. Please look at the actual position (4.c4) for a moment before posting, and you will realize that you have mixed up the lines. It's an isolani structure, not an exchange structure, and a minority attack is just impossible!

So no, he shouldn't study the exchange QG structure, he should study isolani structures. i you want a QG equivalent maybe he could study the QG tarrasch from a white point if view.

Also your comparison with the open sicilian is rather confusing. In the sicilian indeed the central formation is rather stable and so despite his open lines white ofter launches a pawnstorm to archieve something. In this completely different isolani structure a pawnstorm would be utter nonsense and for this precise reason white active play in the centre and down the e file is very important. 

To clarify, I'm not playing 3...d5 transposing into a Panov. Black isn't obliged to do so, and I don't think it's his best option.

Without a pawn on d5, what is White threatening with c4? The pawn duo won't be able to advance easily, and Black can chip away at it with the aid of his b pawn and the open c-file

I said he should study Queen's Gambit Declined positions not just the Carlsbad but IQP and hanging pawns structures too

this clarification is not very clear 

The vast majority of the master games continued with 3...d5, so you should probably specify what is the alternative setup you think is promising. i suppose the pawn goes on d6 soon or later? but then i guess you should go for g6+Bg7 and then white can seriously think about putting the pawn on c3 when the bishop looks rather misplaced.  

Yoe are certainly good enough to understand that without a pawn on d5 white's c4 still serves the purpose of controlling te centre. But nobody said that white is going to play 4.c4 against everything! 

can you please come up with a concrete idea for black? What would you play after 3.exd4 instead of d5? And more importantly, would playing 2...Nf6 and only then your proposed plan have improved or reduced white chances?

indeed my c3 idea is not that good, although black is in no way "much better off"; it's basically a trasposition to the exchange caro which is equal and not better for black; my impression is that you overestrimate the exchange structure for black. The minority attack doesn't mean that the side archieving it is always better; the minority attack is black compensation for white greater piece activity. In itself this structure is not advantageous for one side and depending on the concrete position white can be better (his activity prevents black from playing on the queenside) or indeed better for black (white has no pressure and so black plays freely on the other wing). In no way it can be said "black has the min.att. and so =+". 

Anyway my c3 idea is anemic and harmless, you're right. Probably white should go for c4 anyway, and i think he has a slightly more pleasant game  with more space and pressure on e7, but black no doubt is close to equality. However i think he is much better off if he refrains from this early exchange and plays something like 3...Nf6.

Could you guys clarify what you think is the best continuation against 2. c3 or 2. e3, so that it can be more concise.

Thanks

  I think the problem with playing something like 2...Nf6 is that White can push d5 now and get back into Benoni territory and Black doesn't get the traditional pressure down the e-file since the pawn is not yet on e4.

I definitely like setting up with Nf6, g6 + Bg7. So something like 3...Nf6 4.Nf3 g6 5.Bd3 Bg7 6.O-O O-O and White has to show his hand first, does he want to play c4 and leave d4 potentially weak, play c3 and give Black the minority attack option, or forego either plan for now and develop the knight to c3? Black doesn't have to commit to anything just yet, he can play sensible developing moves (I wouldn't rule out the possibility of the bishop coming to b7 or a6 either) and strike back with d5 at an opportune moment.

 There's rarely one "best" continuation (unless your first name is Hou and second name Dini). Look at the different options and choose one that appeals to you, use your own head