EDB — 00G

[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 \( ¬ (𝛼)\) where \(𝛼\) is a well-formed formula, or

• • a formula of the type \( (𝛼) ⇒ (𝛽) \) , or

  • a formula of the type \( (𝛼) ⇔ (𝛽) \) , or

  • a formula of the type \( (𝛼) ∨ (𝛽) \) , or

  • a formula of the type \( (𝛼) ∧ (𝛽) \) ,

  where \(𝛼,𝛽\) are two well-formed formulas.