bug in polyhedron over RDF

[vdelecroix]

verts = [[159852/261157, 227425/261157],
 [9/10, 7/10],
 [132/179, 143/179],
 [8/11, -59/33],
 [174/167, 95/167],
 [3/2, -1/2],
 [-1162016360399650274197433414376009691155/1045602428815736513789288687833080060779,
  1626522696050475596930360993440360903664/1045602428815736513789288687833080060779],
 [-112565666321600055047037445519656973805313121630809713051718/76591188009721216624438400001815308369088648782156930777145,
  -15318574020578896781701071673537253327221557273483622682053/76591188009721216624438400001815308369088648782156930777145],
 [-222823992658914823798345935660863293259608796350232624336738123149601409997996952470726909468671437285720616325991022633438/141046287872967162025203834781636948939209065735662536571684677443277621519222367249160281646288602157866548267640061850035,
  -20857694835570598502487921801401627779907095024585170129381924208334510445828894861553290291713792691651471189597832832973/28209257574593432405040766956327389787841813147132507314336935488655524303844473449832056329257720431573309653528012370007],
 [-100432602675156818915933977983765863676402454634873648118147187022041830166292457614016362515164/169296796161110084211548448622149955145002732358082778064645608216077666698460018565094060494217,
  -429364759737031049317769174492863890735634068814210512342503744054527903830844433491149538512537/169296796161110084211548448622149955145002732358082778064645608216077666698460018565094060494217]]
P = Polyhedron(verts, base_ring=RDF)
P.faces(1)

with traceback

sage: P.faces(1)
---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
<ipython-input-4-5c776b0f6df7> in <module>()
----> 1 P.faces(Integer(1))

/opt/sage/local/lib/python2.7/site-packages/sage/geometry/polyhedron/base.pyc in faces(self, face_dimension)
   3890             ()
   3891         """
-> 3892         fl = self.face_lattice().level_sets()
   3893         codim = self.dim() - face_dimension
   3894         index = len(fl) - 1 - codim

/opt/sage/local/lib/python2.7/site-packages/sage/misc/cachefunc.pyx in sage.misc.cachefunc.CachedMethodCallerNoArgs.__call__ (build/cythonized/sage/misc/cachefunc.c:13441)()
   2375         if self.cache is None:
   2376             f = self.f
-> 2377             self.cache = f(self._instance)
   2378         return self.cache
   2379 

/opt/sage/local/lib/python2.7/site-packages/sage/geometry/polyhedron/base.pyc in face_lattice(self)
   3814         return Hasse_diagram_from_incidences\
   3815             (atoms_incidences, coatoms_incidences,
-> 3816              face_constructor=face_constructor, required_atoms=atoms_vertices)
   3817 
   3818     def faces(self, face_dimension):

/opt/sage/local/lib/python2.7/site-packages/sage/geometry/hasse_diagram.pyc in Hasse_diagram_from_incidences(atom_to_coatoms, coatom_to_atoms, face_constructor, required_atoms, key, **kwds)
    180     # Make sure that coatoms are in the end in proper order
    181     tail = [faces[atoms, frozenset([coatom])]
--> 182             for coatom, atoms in enumerate(coatom_to_atoms)]
    183     tail.append(faces[A, frozenset()])
    184     new_order = [n for n in new_order if n not in tail] + tail

KeyError: (frozenset([7]), frozenset([3]))

Actually the obtained polygon has 9 vertices and 10 edges

sage: P.n_vertices()
9
sage: P.n_facets()
10

[jipilab]

Perhaps this a is quintessence new polygon that you found there!

[chapoton]

may be related to #18214

[jipilab]

On version 8.8.beta3 I get:

┌────────────────────────────────────────────────────────────────────┐
│ SageMath version 8.8.beta3, Release Date: 2019-04-18               │
│ Using Python 2.7.15. Type "help()" for help.                       │
└────────────────────────────────────────────────────────────────────┘
┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
┃ Warning: this is a prerelease version, and it may be unstable.     ┃
┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛
sage: verts = [[159852/261157, 227425/261157],
....:  [9/10, 7/10],
....:  [132/179, 143/179],
....:  [8/11, -59/33],
....:  [174/167, 95/167],
....:  [3/2, -1/2],
....:  [-1162016360399650274197433414376009691155/1045602428815736513789288687833080060779,
....:   1626522696050475596930360993440360903664/1045602428815736513789288687833080060779],
....:  [-112565666321600055047037445519656973805313121630809713051718/76591188009721216624438400001815308369088648782156930777145,
....:   -15318574020578896781701071673537253327221557273483622682053/76591188009721216624438400001815308369088648782156930777145],
....:  [-222823992658914823798345935660863293259608796350232624336738123149601409997996952470726909468671437285720616325991022633438/141046287872967162025203834781636948939209065735662536571684677443277621519222
....: 367249160281646288602157866548267640061850035,
....:   -20857694835570598502487921801401627779907095024585170129381924208334510445828894861553290291713792691651471189597832832973/2820925757459343240504076695632738978784181314713250731433693548865552430384447
....: 3449832056329257720431573309653528012370007],
....:  [-100432602675156818915933977983765863676402454634873648118147187022041830166292457614016362515164/169296796161110084211548448622149955145002732358082778064645608216077666698460018565094060494217,
....:   -429364759737031049317769174492863890735634068814210512342503744054527903830844433491149538512537/169296796161110084211548448622149955145002732358082778064645608216077666698460018565094060494217]]
....: P = Polyhedron(verts, base_ring=RDF)
....: P.faces(1)
....: 
(A 1-dimensional face of a Polyhedron in RDF^2 defined as the convex hull of 2 vertices,
 A 1-dimensional face of a Polyhedron in RDF^2 defined as the convex hull of 2 vertices,
 A 1-dimensional face of a Polyhedron in RDF^2 defined as the convex hull of 2 vertices,
 A 1-dimensional face of a Polyhedron in RDF^2 defined as the convex hull of 2 vertices,
 A 1-dimensional face of a Polyhedron in RDF^2 defined as the convex hull of 2 vertices,
 A 1-dimensional face of a Polyhedron in RDF^2 defined as the convex hull of 2 vertices,
 A 1-dimensional face of a Polyhedron in RDF^2 defined as the convex hull of 2 vertices,
 A 1-dimensional face of a Polyhedron in RDF^2 defined as the convex hull of 2 vertices,
 A 1-dimensional face of a Polyhedron in RDF^2 defined as the convex hull of 2 vertices,
 A 1-dimensional face of a Polyhedron in RDF^2 defined as the convex hull of 2 vertices)
sage: P.n_vertices()
10
sage: P.n_facets()
10

On stable 8.7, I get:

┌────────────────────────────────────────────────────────────────────┐
│ SageMath version 8.7, Release Date: 2019-03-23                     │
│ Using Python 2.7.15. Type "help()" for help.                       │
└────────────────────────────────────────────────────────────────────┘
sage: verts = [[159852/261157, 227425/261157],
....:  [9/10, 7/10],
....:  [132/179, 143/179],
....:  [8/11, -59/33],
....:  [174/167, 95/167],
....:  [3/2, -1/2],
....:  [-1162016360399650274197433414376009691155/1045602428815736513789288687833080060779,
....:   1626522696050475596930360993440360903664/1045602428815736513789288687833080060779],
....:  [-112565666321600055047037445519656973805313121630809713051718/76591188009721216624438400001815308369088648782156930777145,
....:   -15318574020578896781701071673537253327221557273483622682053/76591188009721216624438400001815308369088648782156930777145],
....:  [-222823992658914823798345935660863293259608796350232624336738123149601409997996952470726909468671437285720616325991022633438/141046287872967162025203834781636948939209065735662536571684677443277621519222
....: 367249160281646288602157866548267640061850035,
....:   -20857694835570598502487921801401627779907095024585170129381924208334510445828894861553290291713792691651471189597832832973/2820925757459343240504076695632738978784181314713250731433693548865552430384447
....: 3449832056329257720431573309653528012370007],
....:  [-100432602675156818915933977983765863676402454634873648118147187022041830166292457614016362515164/169296796161110084211548448622149955145002732358082778064645608216077666698460018565094060494217,
....:   -429364759737031049317769174492863890735634068814210512342503744054527903830844433491149538512537/169296796161110084211548448622149955145002732358082778064645608216077666698460018565094060494217]]
....: P = Polyhedron(verts, base_ring=RDF)
....: P.faces(1)
....: 
(<1,2>, <0,2>, <1,4>, <3,5>, <4,5>, <0,6>, <6,7>, <7,8>, <8,9>, <3,9>)
sage: P.n_vertices()
10
sage: P.n_facets()
10

Should this become a doctest?

[jipilab]

New commits:

​00819d9

Added doctest

[chapoton]

ok, let it be