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Optimization Solver as a Service

quicopt.com

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Re: Optimization Solver as a Service

#31

Post by ge0ffrey »

whatever1 wrote: post #14

We do have standard benchmarks in the field. Hans Mittelman maintains a library. No idea why they did not bother to run them. https://plato.asu.edu/guide.html Their website has just 3 cherry picked instances and claim complete dominance.

We run the Mittelman VRPLib benchmarks at Timefold (and beat other open source solvers like or-tools in 95%+ of the X datasets).

But they are not representive of the real world, at all.

The Mittelman VRPLib benchmarks have only 1-2 constraints. Skills? No need. Working hours? Unlimited. Maps integretion? Cars can fly and the earth is a flat Euclidean space.

Any VRP algorithm optimized for the vrplib datasets is overfitted and not the best one in reality.

Take HGS for instance. Brilliant for CVRPTW. Crumbles to dust in field service routing for telco operations etc.

Re: Optimization Solver as a Service

#34

Post by throwaway832040 »

ge0ffrey wrote: post #26
throwaway832040 wrote: post #25

Earlier quoted context omitted.

None of these solvers genuinely focuses on the quality of the features that matter in real-world operations. Many of them, including Timefold, lack a realistic, financially grounded model of the world. They do not adequately account for traffic, driver preferences, or other factors that require a continuous feedback loop between what actually happened in practice and what the optimizer expected to happen. A vehicle-r…

I beg to differ. Timefold is used daily in real-world operations. Neither our clusters in the US or EU can afford to go down for a minute, or business operations in logistics, retail and healthcare are impacted. > They do not adequately account for traffic, driver preferences, or other factors that require a continuous feedback - Traffic: supported - Driver preferences: the APIs support -- Area affinity (soft) and ge…

[dead]

Re: Optimization Solver as a Service

#35

Post by 6r17 »

TrueDuality wrote: post #6

Really not trying to be cheeky... but why? Who is the audience here? I can see maybe academics with small grants and want to do the absolute minimum spend on compute... But that is an audience you will have to fight for every cent. This doesn't solve or provide guidance for the subtle problems in these otherwise opensource solvers... The first example requires the client to manually disambiguate equivalent variables…

Hei i'd argue the opposite ; the target you named are actually able to formalize this and spend more time on this because they have the mathematical background - it is not the case for many amateur programmer who would now be exposed to such problematic with a tool that can give them somewhat of an insight - being exposed to the tool it-self alone is huge because it allows an operator to experience and learn - this is all of course almost hyperbolic, reality is that most people won't be doing that - but it allows it, and it's cool !

Re: Optimization Solver as a Service

#36

Post by jwally »

For whatever its worth I built this about a decade ago because I am a non academic who can't think in tableaus, but still wanted to solve optimization problems.

I created a json like schema/struct/whatever to describe the problem. Maybe adopt something like this and more people will be able to see how they could use your tool:

https://github.com/JWally/jsLPSolver/blob/master/API.md

I need to re go through the docs, but you get the gist.

Here is the Berlin Airlift problem for example:

const model = { optimize: "capacity", opType: "max", constraints: { plane: { max: 44 }, person: { max: 512 }, cost: { max: 300000 }, }, variables: { brit: { capacity: 20000, plane: 1, person: 8, cost: 5000 }, yank: { capacity: 30000, plane: 1, person: 16, cost: 9000 }, }, };

Re: Optimization Solver as a Service

#37

Post by MILP »

DannyBee wrote: post #13

NEOS will let you run this stuff on cplex/gurobi/etc (IE much faster than the backends behind quicopt), for free, is integrated with pyomo/etc, and has like an 8 hour time limit. Often, the difference on "harder" problems is 10x or more. I have problems that gurobi solves in 30 seconds that take 15 minutes or more for ~every non-commercial solver (or-tools, HIGHS, ipopt, etc). But right now, this wouldn't even be int…

Just curious, what kind of problems are you solving?

Re: Optimization Solver as a Service

#38

Post by LPisGood »

tirutiru wrote: post #18
LPisGood wrote: post #11

Earlier quoted context omitted.

Does anyone use Hexaly for any serious work? If so, why? There seem to be many better alternatives out there.

I'm curious too. And what are the far better alternatives in your opinion? Hexaly claims to go far beyond MIP. Amazon uses it for packing VMs into servers. This video by one of their research scientists was widely circulated at the time [1]. I work on combinatorial optimization too but a specific problem so we write the heuristics from scratch. Seems exact solvers are doing a lot more these days? [1] https://www.yout…

Gurobi is far better for almost every instance I’ve seen. There are also custom heuristics which win in almost every case. Finally, while I have not tried them, there are some apparently high quality options like TimeFold which exist.

Re: Optimization Solver as a Service

#39

Post by LPisGood »

luiwammus wrote: post #17
LPisGood wrote: post #11

Earlier quoted context omitted.

Does anyone use Hexaly for any serious work? If so, why? There seem to be many better alternatives out there.

The main reason why companies might prefer Hexaly is their emphasis on quickly finding high Quality feasible primal solutions.

I get that this is their goal, however they aren’t particularly strong in this area compared to free alternatives, traditional MIP, and custom heuristics.

Re: Optimization Solver as a Service

#40

Post by LPisGood »

whatever1 wrote: post #16
luiwammus wrote: post #15

Earlier quoted context omitted.

Amazon has been quite vocal about using Hexaly.

All vendors just need 1 engineer in a BigCorp to have used their software to claim "Trusted by BigCorpName"

This is essentially my understanding of the situation. The OR applications are extremely diverse there; they use most wvery solver and technique under the sun for something.
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