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Logic Versus Programming

• Aren't programs simpler than logic formulas?
  • Everyday mathematics simpler than programs.
  • Assignment versus equality!
  • Program versus mathematical functions.
• Methods for reasoning about programs based on toy languages.
  • Simpler than real programming languages.
  • More complicated than simple logic.
• Resemblance often misleasing:
  • { x=0 } y:=x+1 { y=x+1 }
  • x:=0; y:=x+1; write(y,x+1)
  • May be different in certain contexts (aliasing)!

Real languages contain difficult concepts because they must yield reasonably efficient programs for complex computers.