Merge branch 'u/soehms/cubic_braid_group_27302' of git://trac.sagemat…

…h.org/sage into cubic_braid_group_27302

src/doc/en/reference/groups/index.rst

@@ -17,6 +17,7 @@ Groups
    sage/groups/finitely_presented
    sage/groups/finitely_presented_named
    sage/groups/braid
+   sage/groups/cubic_braid
    sage/groups/indexed_free_group
    sage/groups/raag
    sage/groups/group_exp

src/doc/en/reference/references/index.rst

@@ -236,6 +236,8 @@ REFERENCES:
 .. [Arn2002] \P. Arnoux, Sturmian sequences, in Substitutions in Dynamics,
              N. Pytheas Fogg (Ed.), Arithmetics, and Combinatorics (Lecture
              Notes in Mathematics, Vol. 1794), 2002.
+.. [Ass1978] \J. Assion: *Einige endliche Faktorgruppen der Zopfgruppen*, Math. Z., 163
+             (1978), 291-302.
 
 .. [ARVT2005] Michael Artin, Fernando Rodriguez-Villegas, John Tate,
               On the Jacobians of plane cubics,
@@ -1371,6 +1373,9 @@ REFERENCES:
 .. [Cox] David Cox, "What is a Toric Variety",
          https://dacox.people.amherst.edu/lectures/tutorial.ps
 
+.. [Cox1957] \H. S. M. Coxeter: *Factor groups of the braid groups*, Proceedings of the Fourth Candian
+             Mathematical Congress (Vancouver 1957), pp. 95-122.
+
 .. [CP2001] John Crisp and Luis Paris. *The solution to a conjecture
             of Tits on the subgroup generated by the squares of the
             generators of an Artin group*. Invent. Math. **145**

src/sage/groups/all.py

@@ -24,6 +24,9 @@
 
 lazy_import('sage.groups.free_group', 'FreeGroup')
 lazy_import('sage.groups.braid', 'BraidGroup')
+lazy_import('sage.groups.cubic_braid', 'CubicBraidGroup')
+lazy_import('sage.groups.cubic_braid', 'AssionGroupU')
+lazy_import('sage.groups.cubic_braid', 'AssionGroupS')
 
 lazy_import('sage.groups.affine_gps.affine_group', 'AffineGroup')
 lazy_import('sage.groups.affine_gps.euclidean_group', 'EuclideanGroup')