Let L : {f1, c1}

Let 2′ := { f2, c1, c2} be a language consisting of one binary function and two constants, and let I’ be the set of formulas
• (Vx)(- fxrix). • (*)(Vy)(Vz)(= f•ryftz -4= yx). • `I iczczoz• Prove formally that I’ I-= c1c2 and briefly explain what the conclusion of this exercise says if f is interpreted as a semigroup operation.