#17979: Reimplementation of IntegerListsLex
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Reporter: aschilling | Owner:
Type: defect | Status: needs_work
Priority: blocker | Milestone: sage-6.6
Component: combinatorics | Resolution:
Keywords: days64 | Merged in:
Authors: Bryan Gillespie, | Reviewers:
Anne Schilling, Nicolas M. Thiery | Work issues:
Report Upstream: N/A | Commit:
Branch: | 39d1993d70a837967109be12de261f4f504901cc
public/ticket/17979 | Stopgaps:
Dependencies: |
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Comment (by nthiery):
Replying to [comment:85 jdemeyer]:
> Replying to [comment:75 bgillespie]:
> > Note that `floor` and `ceiling` take multiple different types of
parameters, not just functions. This code checks for the type of the
input parameter and optimizes when using a constant or a list of integers.
>
> However, without `min_part`, there is absolutely no way to specify
"`floor` is a function which is always at least 1". I should be able to
specify such an input with `floor=myfunc, min_part=1` and the code can
optimize this case better than when just specifying the function.
[comment:60] is an excellent example of this.
We were experimenting a bit with the API to try to minimize redundancy.
At this point, I have settled for:
- `min_part` to specify a lower bound for all parts
- `floor` to specify lower bounds on the individual parts
What do you think?
Question: if the users passes `floor=f, min_part=i` should
`IntegerListsLex` assume that `f(k)` is always at most `i`, or should it
wrap `f` to add this guarantee? At this point it does the latter, which of
course adds a bit of overhead (which could be tamed with appropriate
caching which we will anyway want to do during the Cythonization).
--
Ticket URL: <http://trac.sagemath.org/ticket/17979#comment:105>
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