Definition checkPrfEQ2 (p recs : nat) :=
  charFunction 2 beq_nat (cPairPi2 (cPairPi2 p)) 0 *
  charFunction 2 beq_nat
    (codeFormula L codeF codeR
       (fol.impH L (fol.equal L (fol.var L 0) (fol.var L 1))
          (fol.equal L (fol.var L 1) (fol.var L 0)))) 
    (cPairPi1 p).

Lemma checkPrfEQ2IsPR : isPR 2 checkPrfEQ2.