1# back references, ugh 2a\(b\)\2c bC ESUBREG 3a\(b\1\)c bC ESUBREG 4a\(b*\)c\1d b abbcbbd abbcbbd bb 5a\(b*\)c\1d b abbcbd 6a\(b*\)c\1d b abbcbbbd 7^\(.\)\1 b abc 8a\([bc]\)\1d b abcdabbd abbd b 9a\(\([bc]\)\2\)*d b abbccd abbccd 10a\(\([bc]\)\2\)*d b abbcbd 11# actually, this next one probably ought to fail, but the spec is unclear 12a\(\(b\)*\2\)*d b abbbd abbbd 13# here is a case that no NFA implementation does right 14\(ab*\)[ab]*\1 b ababaaa ababaaa a 15# check out normal matching in the presence of back refs 16\(a\)\1bcd b aabcd aabcd 17\(a\)\1bc*d b aabcd aabcd 18\(a\)\1bc*d b aabd aabd 19\(a\)\1bc*d b aabcccd aabcccd 20\(a\)\1bc*[ce]d b aabcccd aabcccd 21^\(a\)\1b\(c\)*cd$ b aabcccd aabcccd 22