6. = a. Let L be a logical language and let Cn(A) = {a | A Fa} be the consequence closure of A CL where is the classical
Posted: Thu May 12, 2022 10:05 am
6. = a. Let L be a logical language and let Cn(A) = {a | A Fa} be the consequence closure of A CL where is the classical consequence relation. For each question, if the answer is yes, then give a proof, otherwise give a counterexample. i. If A, C A, holds, does Cn(41) Cn(42) hold? [4 marks) ii. If A has no models, does Cn(A) = L hold? (4 marks) iii. Does Cn(A1) U Cn(42) = Cn(A, UA2) hold? [4 marks)