Why is $()$q$)$

not a well$-$formed formula? Choose ALL statements that apply in $($possibly different$)$ proof$($s$)$ by analysis of formula calculation.

Question $4$Answer

a$.$

It is of the form $($A$$B$)$

but A

cannot be written at any step of a formula calculation

b$.$

$)$

cannot be written at any step of a formula calculation because it is not a Boolean variable or constant and doesn't contain any connectives

c$.$

Considering $()$q$)$

in the form $($A$$B$)$

$,$ we see that A

is $()$

which cannot be written at any step of a formula calculation because it does not contain any connectives

d$.$

It is not of the form $($A$)$

since it ends with q

and not $)$

e$.$

It is not a Boolean variable or constant because it begins with $($