Chess Board
[ECO code A00]
TRANSPOSITION
SARAGOSSA OPG. to QGD EXCHANGE VAR.
Black advanced his QPawn to Q4(d5) to prevent 4.P-K4, and created a fixed centre (ie. mutually blocked pawns after an exchange on adjoining files).
White develops his Queen's Knight to QB3(c3), threatens Black's queen's pawn and supports P-K4.
    White  Black    Transp.White Black
 1. P-QB3  P-K4	    (1.	P-Q4   P-Q4)
 2. P-Q4   PxP	    (2.	P-QB3  P-K3)
 3. PxP	   P-Q4	    (3.	PxP    PxP )
 4. Kt-QB3	    (4.	Kt-QB3	   )
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