[00G] (Solved on 2022-10-11) Well-formed formulas are
atomic formulas, i.e. composed of a single variable, or
a formula of the type Β¬(πΌ) where πΌ is a well-formed formula, or
a formula of the type (πΌ)β(π½) , or
a formula of the type (πΌ)β(π½) , or
a formula of the type (πΌ)β¨(π½) , or
a formula of the type (πΌ)β§(π½) ,
where πΌ,π½ are two well-formed formulas.