handling more general expressions

[fserra]

SCIP allows for user defined expressions. One could in principle give the evaluations via callbacks (as I guess other solvers do), in case we cannot understand the expression provided to MPB.
This is probably future future work

[rschwarz]

I thought we would evaluate neither functions nor derivates and instead just look at the expression graphs. If there's something we don't understand, we should just fail.

[fserra]

that is the current functionality... I just though it might be nice to also provide support for weird user defined stuff.

[mlubin]

You're pretty screwed if you're solving a nonconvex MINLP without expression graphs

[fserra]

sure, but if some crazy user wants to have some :ifelse in their expression graph, he/she/it is completely screwed.

On Mon, Sep 5, 2016 at 5:12 PM, Miles Lubin notifications@github.com wrote:

You're pretty screwed if you're solving a nonconvex MINLP without expression graphs

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[mlubin]

A lot of expressions involving ifelse can be reformulated using binary variables. ifelse is more relevant for continuous NLP.

[fserra]

well, this could still be useful for convex minlp, right?

[mlubin]

No, use Pajarito :)