(error present at least from SageMath 8.2 until SageMath 9.8) On Monday, April 17, 2023 at 12:36:41 AM UTC-6 Tracy Hall wrote:
> Attempting to calculate the centralizer of a particular element of the > braid group on 5 strands causes a segmentation fault. > > sage: BG = BraidGroup(5); BG > Braid group on 5 strands > > sage: b = BG([3, 3, 4, 3, 3, 2, 1, 4, 3, 2]); b > s2^2*s3*s2^2*s1*s0*s3*s2*s1 > > sage: b.left_normal_form() > (1, s2*s3*s2, s2*s1*s0*s3*s2*s1*s0) > > sage: b.ultra_summit_set() > [[s0*s1*s0*s2*s1*s0*s3*s2*s1*s0]] > > sage: b.is_pseudoanosov() > False > > sage: b.centralizer() > --------------------------------------------------------------------------- > SignalError Traceback (most recent call last) > Cell In [7], line 1 > ----> 1 b.centralizer() > File /ext/sage/9.8/src/sage/groups/braid.py:1546, in > Braid.centralizer(self) > 1534 def centralizer(self): > 1535 """ > 1536 Return a list of generators of the centralizer of the braid. > 1537 > (...) > 1544 > 1545 """ > -> 1546 l = centralizer(self) > 1547 B = self.parent() > 1548 return [B._element_from_libbraiding(b) for b in l] > File /ext/sage/9.8/src/sage/libs/braiding.pyx:233, in > sage.libs.braiding.centralizer() > 231 return [[[0], [i+1, nstrands - i -1]] for i in > range(nstrands//2-1)] + [[[0], [nstrands//2]]] > 232 l = braid.Tietze() > --> 233 sig_on() > 234 cdef list[list[list[int]]] rop = CentralizerGenerators(nstrands, l) > 235 sig_off() > SignalError: Segmentation fault > -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-support/be9455fb-ab03-43bb-93f2-dd3a2c43186bn%40googlegroups.com.
