# File Warshall.rb, line 272 def vereinigt(rel) erg = Relation.new([[]]) erg.basis!(@basis + rel.basis) erg.each{|i| erg.nach[i] = (@nach[i]==nil ? Menge.new([]) : @nach[i]) + rel.nach[i] } erg.each{|i| erg.vor[i] = (@vor[i]==nil ? Menge.new([]) : @vor[i]) + rel.vor[i] } return erg end