The Logic Resource Center

Public Alpha

Public Alpha

De Morgan

De Morgan's Laws express the interdefinability of conjunction, negation and disjunction.

i.

(¬ϕ&¬ψ)

⋮

ii.

¬(ϕ∨ψ)

DeM: i

i.

(¬ϕ∨¬ψ)

⋮

ii.

¬(ϕ&ψ)

DeM: i

i.

¬(ϕ&ψ)

⋮

ii.

(¬ϕ∨¬ψ)

DeM: i

i.

¬(ϕ∨ψ)

⋮

ii.

(¬ϕ&¬ψ)

DeM: i

Preview shown for the Point And Click derivation type in the OLI system