I am trying to solve this exercise
Exercise: 1 star, standard (subtype_instances_tf_2)
from this chapter
This statemen below. Is it true?
∃S, S <: S→S
This is what I think about it:
Going to use 2 rules:
S_Refl and S_Arrow
S <: S->S ??? is it true or false, let’s try Exists (S->S)
S -> S <: (S -> S) -> (S -> S)
S1 S2 T1 T2 According to S_Arrow we should have 2 statements
Statement 1. (S -> S) <: S
Statement 2. S <: (S -> S)
but it is a contradiction. So answer is False? Is it correct? is it a contradiction?