def get_proof_term(self, thy, t):
if t.ty != Term.COMB:
return refl(t)
f, c = t.fun, t.arg
if is_fun_upd(f):
f1, a, b = f.args
if a == c:
return rewr_conv("fun_upd_same").get_proof_term(thy, t)
else:
neq = nat.nat_const_ineq(thy, c, a)
eq = rewr_conv("fun_upd_other",
conds=[neq]).get_proof_term(thy, t)
return eq.on_arg(thy, self)
elif f.is_abs():
return ProofTerm.beta_conv(t)
else:
return refl(t)
def get_proof_term(self, thy, t):
try:
return ProofTerm.beta_conv(t)
except InvalidDerivationException:
raise ConvException()