Not taking grammar into account (spaces, periods, etc.) the number of ciphertexts possible from every plaintext of length N is exactly 1, i.e. the set P of 26N plaintexts maps into the set C of 1 ciphertext. As the number of possible ciphertexts is less than the number of possible plaintexts and there is no way of calculating redundancy, it is impossible to decipher pipelang for any ciphertext.