Direct Transposition?

Hello.

I just want to know how can we determine if a certain position is a transposition from one opening to another.

For example : Is it just that 1.c4 Nf6 2.Nc3 d6 3.e4 g6 4.d4 Bg7 is a direct transposition of 1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6 because they have the same position both at move 4?

 Here is a particular game that I'm quite interested with. If I haven't played it, I'd certainly say it was a yugoslav dragon if given this position

So, does that mean if I look at the theory and find the same exact position in a Yugoslav Dragon at move 11, the Pirc and the Sicilian Dragon transposed to each other?

Anyway, I'm just asking to clarify how transposition really works. Oh and since I'm on it, is 4.Bg5 a good move? I thought of 4.Be3, but I see that it's more aggresive at g5.

Please discuss.

Yes, you have the right idea of "transposition". It simply means arriving at the same position using a different sequence of moves. In this case, one would say that the Pirc transposed into the Sicilian Dragon.

Hmmm, if that is so, what is the possible move order? I'm trying to figure it out, but I think it isn't really a direct transposition. Just a similar position.

This is no Yugoslav Dragon.

The Yugoslav is defined by Bc4 (here we have Bd3), and the QN goes to c6 (not d7), and Black's q-side fianchetto would be pretty lame in the Dragon.

I think that your position is better for White than a standard Dragon.

I agree.

In the position, Black's attack on the Qside is considerably slow. His pawns, the absence of the rook on the c-file, and the bishop on b7 which is biting on granite all gives me a clean advantage.

Black is definitely worse, he has no attack. As Black, I'd offer a draw and excuse myself from the board. However, if I cannot, I would play d5.

You hit the nail in the head.  A direct transposition is the exact same position arrived from a different move order, and sometimes a completely different opening.

Very common transpositions include (there are many others of course, but these are some of the most common):

English and Reti, in both directions.  1.c4 e6 2.Nf3 d5 is a Reti while 1.Nf3 c5 2.c4 Nf6 is an English.

English and King's Indian Defense.  Basically the line you indicated above.

Nimzo-Indian and Queen's Gambit Declined.  1.d4 Nf6 2.c4 e6 3.Nc3 d5 is no longer a Nimzo-Indian, it's a QGD.

English Defense and French or Owen's Defense.  Those that play the English Defense against 1.d4 have to watch out for tranpositions.  If you normally play 1.d4 b6 2.c4 e6, you have to deal with Owen's Defense, 2.e4 with no c4 push (i.e. 3.Nc3).  If you normally play 1.d4 e6 2.c4 b6, you have the French Defense to deal with.  If you are like me, and only play the English Defense against 1.c4, which I do maybe half the time I face 1.c4, then you have lines with no d4 to deal with, like 1.c4, 2.Nc3, and 3.e4 (The two prong attack) or 1.c4 e6 2.Nc3 b6 3.Nf3 Bb7 4.g3 Bxf3 5.exf3, for example.

I personally had a weird one in January of this year over the board.  Started out a Pirc, and transposed to a Levenfish Dragon.  Game went 1.e4 d6 2.d4 Nf6 3.Nc3 g6 4.f4 c5 (a little odd, but I allowed the transposition to the Levenfish with 5.Nf3, and after 5...cxd4 6.Nxd4, we are in the same position as after 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 g6 6.f4.  This guy obviously didn't know how to play a Dragon, and by move 13 I (White) was completely won, and he resigned at move 30.

There are of course others to deal with as well, but this gives you some idea of common ones to expect.