Unique Representation

asked 2012-10-23 00:00:23 +0100

SLOtoSF
107 ●7 ●13 ●19

updated 2012-10-23 00:05:09 +0100

Please explain why the following output is as so. How is it possible for id's not to match but the names to be equal?

sage: SP = SetPartitions(5)
sage: a = SetPartitions(5).random_element()
sage: a
{{2, 3, 4, 5}, {1}}
sage: id(a)
190399916
sage: a in SetPartitions(5)
True
sage: a in SP
True
sage: print id(SP); print id(SetPartitions(5))
188090924
188091308
sage: SP == SetPartitions(5)
True

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answered 2012-10-23 08:49:30 +0100

Hivert
161 ●4 ●7

Currently in Sage, SetPartitions are not proper Parent and uses the old deprecated CombinatorialClass framework. This framework was writen before UniqueRepresentation. As a consequence

sage: isinstance(SetPartitions(5), UniqueRepresentation)

False

We are currently in the process of removing CombinatorialClass and cleaning the code depending of it. See for example trac ticket #13552, #12913, #9265. Nothing is currently done on set partitions.

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Asked: 2012-10-23 00:00:23 +0100

Seen: 324 times

Last updated: Oct 23 '12

Unique Representation edit

1 Answer