LLMs can't optimize schedules...
but AI can.

by Tom Cools

Gemini (Nano Banana Pro): "A cat sitting on a crocodile while playing the banjo"
Gemini (Nano Banana Pro): "A cat in a tiny top hat hosting a stand-up comedy show for a crowd of impressed goldfish"

GenAI Is Awesome πŸš€

Solution for EVERYTHING 🀯

or is it? πŸ€”

What is something
LLMs can't do?

7 days

5 shifts per employee

30 employees

150 shift assignments

5 constraints (skills, time between shifts, etc.)

How do LLMs solve
my planning problem?

LLMs πŸšΆβ€β™‚οΈπŸŒ³ β˜€οΈ

Can reasoning models optimize a realistic schedule?

That is "slightly" over-optimistic

Visualization of "completed" schedule

Why do LLMs fail here?

Scheduling is not a sequence of decisions

30 employees

150 shift assignments

How many different solutions?


1 shift: 30 options

2 shifts: 30*30 options

3 shifts: 30^3 options

150 shifts: 30^150 options

150 shifts: 30^150

3.69 Γ— 10^221

Atoms in the observable universe: 10^80

10^221: 141 more zeroes

You can't optimize for such a search space

by predicting the next token
nor by reasoning like a human.

LLMs can't optimize schedules

... but AI can!

Machine Learning

Machine learning is a branch of AI where systems learn patterns from data to make predictions or decisions without being explicitly programmed.

Machine Learning is Awesome πŸš€

Can Machine Learning be used
to optimize schedules?

Learn from data...

but what data?

Interlinked Decisions

Mathematical Optimization

Group of techniques to find the ideal inputs from a set
in order to maximize or minimize a real function.
$\begin{aligned} & \quad \sum_{s \in S} \sum_{e \in E} \mathrm{pref}(s,e) \, a_{s,e} \\ \end{aligned} $

Planning optimization made easy


  • Optimization algorithms in domain code
  • Open Source (Apache license)
  • JVM based!

Demo

πŸ–Š Model domain

βš–οΈ Define constraints

πŸš€ Run!

Example Usecases

🚚 Vehicle Routing πŸ§‘β€πŸ’Ό Employee Scheduling
πŸ› οΈ Maintenance Scheduling πŸ“¦ Food Packaging
πŸ›’ Order Picking 🏫 School Timetabling
🏭 Facility Location Problem 🎀 Conference Scheduling
πŸ›οΈ Bed Allocation Scheduling πŸ›« Flight Crew Scheduling
πŸ‘₯ Meeting Scheduling βœ… Task Assigning
πŸ“† Project Job Scheduling πŸ† Sports League Scheduling
πŸ… Tournament Scheduling ...and many more

Does Optimization Matter?

Vehicle Routing Case

Expected: -1% driving time

Result: -25% driving time

β‡’ -10 million kg COΒ² emission per year

β‡’ -100 million $ cost per year

LLMs can't optimize schedules
but AI can!

Future of AI?

Let GenAI write
the code

Source: https://github.com/algorithmicsuperintelligence/openevolve (Apache Licensed)
Source: https://github.com/algorithmicsuperintelligence/openevolve (Apache Licensed)
From Devoxx founder Stephan Janssen: https://github.com/stephanj/conference-scheduling-skill

To Conclude

GenAI Is Awesome πŸˆβ€β¬›

...but it can't do everything...

All feedback and ratings are encouraged

solver.timefold.ai

Add me on socials! πŸ™ Tom Cools: (@tomcools.be)