@article{Mateescu_Salomaa_Yu_2002, title={Factorizations of languages and commutativity conditions}, volume={15}, url={https://cyber.bibl.u-szeged.hu/index.php/actcybern/article/view/3583}, abstractNote={Representations of languages as a product (catenation) of languages are investigated, where the factor languages are "prime", that is, cannot be decomposed further in a nontrivial manner. In general, such prime decompositions do not necessarily exist. If they exist, they are not necessarily unique - the number of factors can vary even exponentially. The paper investigates prime decompositions, as well as the commuting of the factors, especially for the case of finite languages. In particular, a technique about commuting is developed in Section 4, where the factorization of languages L1 and L2 is discussed under the assumption L1L2 = L2L1.}, number={3}, journal={Acta Cybernetica}, author={Mateescu, Alexandru and Salomaa, Arto and Yu, Sheng}, year={2002}, month={Jan.}, pages={339-351} }