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Informal description: ""

{λ[a:Prop] .​ λ[b:Prop] .​ λ[i:{((b) .​ not ) .​ ((a) .​ not )} .​ imp ] .​ λ[j:{((a) .​ not ) .​ ((b) .​ not )} .​ imp ]} .​ <{(b) .​ (a)} .​ iff > .​ {({(i) .​ (a) .​ (b)} .​ cp ) .​ ({(j) .​ (b) .​ (a)} .​ cp ) .​ (b) .​ (a)} .​ iffi

Validation parameters: sort hierarchy = "Z2", kernel options = ""