import proveit
# Prepare this notebook for defining the axioms of a theory:
%axioms_notebook # Keep this at the top following 'import proveit'.
from proveit.logic import Forall, Equals
from proveit import a, b, c
from proveit.numbers import Add, Neg, zero, Natural
%begin axioms
negation_is_injunctive = Forall((a, b), Equals(a, b), condition=[Equals(Neg(a), Neg(b))], domain=Natural)
# By default, Add(a, Neg(a)) will display in the subtraction style (the same as subtract(a, a))
neg_def_add_inv = Forall((a, b, c), Equals(Add(c, Neg(a)), b),
conditions=[Equals(Add(a, b), c)],
domain=Natural)
%end axioms