- 04 Jun 2018, 00:28
- Forum: Helpdesk
- Topic: ERROR: no matching overloaded instance of...
- Replies:
**3** - Views:
**300**

The function homology expects the list of facets as the first argument, not the entire `big' object. You can verify this by looking at the list of argument types produced by help "topaz::homology"; The name of the first argument is "complex" which might be in fact misleading. In your example you sho...

- 07 Mar 2018, 09:32
- Forum: Helpdesk
- Topic: Corrupt or incomplete installation
- Replies:
**2** - Views:
**363**

Which polymake version are you using? If it's not the recently released 3.2, would you mind migrating to it?

- 07 Mar 2018, 09:29
- Forum: Helpdesk
- Topic: Running into error with 3.2 installation
- Replies:
**13** - Views:
**1479**

Another option is to run polymake docker image, it comes equipped with ppl 1.2 (and many other things).

- 02 Mar 2018, 19:44
- Forum: Helpdesk
- Topic: Discrepancy in computing facets of a mixed integer program
- Replies:
**29** - Views:
**1941**

Hmm, at least you should deal with them differently when importing them as input, shouldn't you?it makes a minor difference in my codes whether something is an equality or an inequality, so I somehow lost some theoretical understanding.

- 02 Mar 2018, 11:33
- Forum: Helpdesk
- Topic: Discrepancy in computing facets of a mixed integer program
- Replies:
**29** - Views:
**1941**

Every Polytope object has FACETS and AFFINE_HULL, the latter can just be empty (more precisely, is a matrix with 0 rows) when the polyhedron is full-dimensional. FACETS are by definition non-trivial inequalities, that is, for every facet there is at least one vertex point not lying in the hyperplane.

- 02 Mar 2018, 09:55
- Forum: Helpdesk
- Topic: Discrepancy in computing facets of a mixed integer program
- Replies:
**29** - Views:
**1941**

I use polymake to get the facets of these 3104 lattice points. They are Dx <= e Now, when solve the linear program Min Cx Such that Ax <= b, Dx <= e, x can be continuous I expect to get the optimal solution value of 178. Unfortunately, I do not get 178 but instead get a number lower than this. Coul...

- 02 Mar 2018, 09:48
- Forum: Helpdesk
- Topic: Discrepancy in computing facets of a mixed integer program
- Replies:
**29** - Views:
**1941**

Then AffineHull is exactly what I said, the equations defining the linear span. If there are some, they must be taken together with Facets, not instead of! And they are equations, not inequalities. So you must have computed the second LP on a polyhedron of a much higher dimension!

- 02 Mar 2018, 00:29
- Forum: Helpdesk
- Topic: Discrepancy in computing facets of a mixed integer program
- Replies:
**29** - Views:
**1941**

Well, there are not that many ways to define a facet, I guess. The only source of confusion I could imagine might be the concrete matrix representation: if you have a linear system A*x <= B, you have to specify INEQUALITIES and FACETS as a block matrix (B | -A) because polymake's polyhedra are alway...

- 01 Mar 2018, 22:09
- Forum: Helpdesk
- Topic: Discrepancy in computing facets of a mixed integer program
- Replies:
**29** - Views:
**1941**

I am not an expert on how Polymake handles LPs/polyhedra. There is absolutely no magic. You create a Polytope object with INEQUALITIES and EQUATIONS, then add an LP subobject with LINEAR_OBJECTIVE vector and ask for LP.MINIMAL_VALUE or LP.MAXIMAL_VALUE or LP.MINIMAL_VERTEX or LP.MAXIMAL_VERTEX. Dep...

- 01 Mar 2018, 20:46
- Forum: Helpdesk
- Topic: Discrepancy in computing facets of a mixed integer program
- Replies:
**29** - Views:
**1941**

... Unless I am missing something obvious, this seems like a bug in polymake. Sorry, I've kind of got lost in the lengthy discussion, it contains several possible solutions to the same problem achieved after different roundings and other modifications. Could you please reformulate this claim as a s...

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