Please use the graphical technique.
Here is an example of it:
http://www.diag.uniroma1.it/liberato/planning/tableau/multiple-04.png
The auxiliary hypothesis is: "Suppose that Γ ⊢ (∃x)A."
I don't understand the technique. Can you give a definition rather than an example?
The auxiliary hypothesis is: "Suppose that Γ ⊢ (∃x)A."
I don't understand the technique. Can you give a definition rather than an example?