Translate The following passage Define your terms eg A B I

Translate The following passage. Define your terms (e.g. A =......, B =.......). Is The argument valid or invalid? \"Unless both Mary goes and Henry goes, The party will be a disaster. The party will be a disaster. Therefore, both Mary and Henry will not go.\"

Solution

A=Mary goes, B=Henry goes, C=Party will be a disaster

Both Mary goes and Henry goes = A and B

Unless both mary goes and henry goes, the party will be a disaster: ~(A and B)->C

The party will be a disaster: C

Both Mary and Henry will not go: ~A and ~B

The argument is not valid since if A=T, B=T and C=T, the premises are all true:

~A and ~B -> C is true, C is true

but the conclusion is ~T and ~T=F and F = F which is false.