A57: Benko gambit, Nescafe Frappe attack

A57 Sub-variants:

• Benko gambit
  1. d4 Nf6 2. c4 c5 3. d5 b5
• Benko gambit half accepted
  1. d4 Nf6 2. c4 c5 3. d5 b5 4. cxb5 a6
• Benko gambit, Zaitsev system
  1. d4 Nf6 2. c4 c5 3. d5 b5 4. cxb5 a6 5. Nc3
• Benko gambit, Nescafe Frappe attack
  1. d4 Nf6 2. c4 c5 3. d5 b5 4. cxb5 a6 5. Nc3 axb5 6. e4 b4 7. Nb5 d6 8. Bc4