TY - JOUR TI - CJM volume 71 Issue 2 Cover and Front matter JO - Canadian journal of mathematics PY - 2019 SP - f1 EP - f2 VL - 71 IS - 2 UR - http://geodesic.mathdoc.fr/articles/10.4153/S0008414X19000099/ DO - 10.4153/S0008414X19000099 ID - 10_4153_S0008414X19000099 ER -