#20559: InteractiveLPProblem, dictionaries: add_constraint / add_row methods
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Reporter: mkoeppe | Owner:
Type: enhancement | Status: needs_work
Priority: major | Milestone: sage-7.2
Component: linear | Resolution:
programming | Merged in:
Keywords: | Reviewers: Andrey Novoseltsev
Authors: Peijun Xiao | Work issues: rebasing
Report Upstream: N/A | Commit:
Branch: | 206d5ca51bb4a2cfe121caf21db7f1afb76e9037
u/mkoeppe/interactivelpproblem__dictionaries__add_constraint___add_row_methods|
Stopgaps:
Dependencies: #20500 |
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Comment (by mkoeppe):
Replying to [comment:17 novoselt]:
> Replying to [comment:11 mkoeppe]:
> > No, no, it's crucial that `add_row` is supported by abstract
dictionaries.
> > The whole point is to have a method that adds a row to the dictionary,
no matter how the dictionary is internally represented. This is the
operation needed by tableau cutting plane procedures.
> > In the revised dictionary, one needs to do this kind of transformation
to compute the new row of the problem, which gives the desired tableau
row. (This is how tableau cutting planes are actually implemented in
numerical solvers.)
>
> OK, let's have it, but I still find the name confusing - can it be
`add_relation`? While for the revised dictionaries it will add a row to
the only of the two tables that can get an extra row, data there will not
be the provided coefficients. Hence I'd like something more conceptual
than layout reference.
"add_relation" wouldn't express the operation well; because we're not just
adding a relation but also a new basic variable.
I've never heard anyone call this operation other than "adding a row"
(whether it's a textbook dictionary or a revised dictionary).
Also note that "row" matches the method `row_coefficients`.
--
Ticket URL: <http://trac.sagemath.org/ticket/20559#comment:22>
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