Hint Resolve N_larger_bound_mod : eval.

Lemma exp_mod_aux_correct y: forall x m tx ty tm b tb,
m <> 0 ->
N_larger_bound m b ->
evaluates tx (value_of_N x) ->
evaluates ty (value_of_pos y) ->
evaluates tm (value_of_N m) ->
evaluates tb (value_of_pos b) ->
evaluates (exp_mod_auxF (: tx, ty, tm, tb :))
( x ^ (Npos y) mod m).