[ot][spam][personal] nothing is impossible

[Undescribed Horrific Abuse, One Victim & Survivor of Many]

a=1
b=2
prove that a+b=3
disprove that a+b=4

# in a proof situation, we are temporarily writing as if the axioms
are always true.
# there are additionally hidden axioms which are the rules used for the proof.
# hence, our conclusion is true only under the conditions that all of the axioms
# and all of the rules are also true.
# this difference can come into play in formal logic where “if” has a
nonintuitive meaning

# hard
# could use formalization of meaning of + and = with variables and literals
a+b=1+2
1+2=3
a+b=3
3!=4
a+b!=4
# could use formalization of meaning of = and != and relation to prove
and disprove

# how did the contradiction arise from constraints on the parts?
# maybe within the meanings of e.g. = .