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citations	visibility	version 1	version 1	(static HELM directory)	helena

Informal description: ""

{λ[a:Prop] .​ λ[b:Prop] .​ λ[n:(a) .​ not ] .​ λ[b1:b]} .​ <({(b) .​ (a)} .​ iff ) .​ not > .​ {({(n) .​ (b1) .​ (a) .​ (b)} .​ th4 ) .​ ({(a) .​ (b)} .​ imp ) .​ ({(b) .​ (a)} .​ imp )} .​ th2

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