Consider the statement A “□A → B and □B → A” and the statement B “□A → B and □B → A and false”
Why are those two statements not provable in every system in which they can be written?
Consider the statement A “□A → B and □B → A” and the statement B “□A → B and □B → A and false”
Why are those two statements not provable in every system in which they can be written?