Chess Opening Theory/1. d4/1...Nf6/2. c4/2...c5/3. d5/3...b5/4. cxb5

= Benko Gambit =

4. cxb5
White accepts the initial gambit. Black usually now plays ...a6, taking back with the bishop if white accepts.

Theory table
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'''1. d4 Nf6 2. c4 c5 3. d5 b5 4. cxb5'''