revconsapp C x1 x2 r revconsapp x2 C x1 r deeprevapp C x1 x2 rest deeprevapp x2 C x1 rest deeprevapp V n rest revconsapp rest V n deeprevapp N rest rest revconsapp V n r r revconsapp N r r deeprev C x1 x2 deeprevapp C x1 x2 N deeprev V n V n deeprev N N second V n N second C x1 x2 x2 isVal C x1 x2 False isVal V n True isVal N False isNotEmptyT C x1 x2 True isNotEmptyT V n False isNotEmptyT N False isEmptyT C x1 x2 False isEmptyT V n False isEmptyT N True first V n N first C x1 x2 x1 goal x deeprev x revconsapp 2 C 2 deeprevapp 2 V 1 N 0 deeprev 1 second 1 isVal 1 False 0 True 0 isNotEmptyT 1 isEmptyT 1 first 1 goal 1 INNERMOST