@Article{ Lohrey01mfcs, author = "Lohrey, Markus", title = "Word Problems for 2-Homogeneous Monoids and Symmetric Logspace", year = "2001", volume = "2136", pages = "500--511", publisher = "Springer", address = "Berlin", series = "Lecture Notes in Computer Science", booktitle = "26th International Symposium, MFCS 2001 Marianske Lazne, Czech Republic, August 27-31, 2001 Proceedings", doi = "10.1007/3-540-44683-4_44" }