subsetsConsxxssubsets[Ite][True][Let]ConsxxssubsetsxssubsetsNilConsNilNilmapconsappx'ConsxxsrestConsConsx'xmapconsappx'xsrestmapconsappxNilrestrestnotEmptyConsxxsTruenotEmptyNilFalsegoalxssubsetsxssubsets[Ite][True][Let]Consxxssubsmapconsappxsubssubssubsets[Ite][True][Let]2True0subsets1Cons2Nil0mapconsapp3notEmpty1goal1False0INNERMOST