@article{JEMS_2011_13_6_a2,
     author = {Jean Fromentin},
     title = {Every braid admits a short sigma-definite expression},
     journal = {Journal of the European Mathematical Society},
     pages = {1591--1631},
     publisher = {mathdoc},
     volume = {13},
     number = {6},
     year = {2011},
     doi = {10.4171/jems/289},
     url = {http://geodesic.mathdoc.fr/articles/10.4171/jems/289/}
}