4 goals
case decidable.is_false, decidable.is_false
p q : Prop
⊢ ¬p → ¬q → true

case decidable.is_false, decidable.is_true
p q : Prop
⊢ ¬p → q → true

case decidable.is_true, decidable.is_false
p q : Prop
⊢ p → ¬q → true

case decidable.is_true, decidable.is_true
p q : Prop
⊢ p → q → true
4 goals
case pos, pos
p q : Prop,
_inst_1 : decidable p,
_inst_2 : decidable q
⊢ q → p → true

case pos, neg
p q : Prop,
_inst_1 : decidable p,
_inst_2 : decidable q
⊢ ¬q → p → true

case neg, pos
p q : Prop,
_inst_1 : decidable p,
_inst_2 : decidable q
⊢ q → ¬p → true

case neg, neg
p q : Prop,
_inst_1 : decidable p,
_inst_2 : decidable q
⊢ ¬q → ¬p → true