Wednesday, March 11, 2026

What did Paul Erdos quip about aliens and R(6,6)

In extremal combinatorics, AlphaEvolve has helped establish new lower bounds for FIVE classical Ramsey numbers - a problem so challenging that even ErdÅ‘s commented on its difficulty 

The statement “AlphaEvolve has helped establish new lower bounds for five classical Ramsey numbers” is significant because it represents progress in one of the hardest areas of combinatorics and theoretical mathematics. To understand why it matters, we need to unpack a few pieces.


1. What Ramsey numbers are

Ramsey numbers come from Ramsey Theory, which studies when order must appear inside randomness.

A Ramsey number (R(m,n)) asks:

What is the smallest number of people needed at a party so that either at least (m) people all know each other or at least (n) people are all strangers?

Example:

  • Ramsey number R(3,3) = 6

Meaning:

  • In any group of 6 people, there must be either:

    • 3 mutual friends, or

    • 3 mutual strangers.

For larger numbers (like (R(5,5)), (R(6,6))), the values become extremely hard to determine.


2. Why Ramsey numbers are notoriously difficult

Most Ramsey numbers are unknown.

For example:

  • Ramsey number R(5,5) is only known to be between 43 and 48.

  • For larger ones, the uncertainty ranges can be hundreds or thousands wide.

Mathematicians usually try to prove:

  • Lower bound: the number is at least some value

  • Upper bound: the number is at most some value

Closing the gap between these bounds is a major research challenge.


3. What a “new lower bound” means

If researchers show a larger lower bound, it means they discovered a specific structure that avoids the forced pattern longer than previously known.

Example idea (simplified):

Previously:

  • Largest known graph avoiding the pattern: N = 42

New result:

  • Someone constructs one with N = 44

Now we know:

[
R(m,n) > 44
]

That’s a new lower bound.

Even improving by 1 can be a major breakthrough.


4. What AlphaEvolve did

AlphaEvolve is an AI system developed by Google DeepMind that searches for mathematical structures.

Instead of proving theorems directly, it:

  1. Generates candidate graphs

  2. Tests whether they avoid certain forbidden patterns

  3. Evolves better structures using search and optimization

Using this process, it discovered larger graphs without certain cliques or independent sets, improving known bounds.

So when you read:

“AlphaEvolve established new lower bounds for five classical Ramsey numbers”

it means:

  • The AI found better constructions than humans previously knew.

  • Those constructions push the known limits of these Ramsey numbers.


5. Why this is a big deal

There are several reasons mathematicians care:

1. These problems can remain unsolved for decades

Some Ramsey bounds haven't improved in 20–30 years.

2. The search space is astronomically large

For graphs with 40–50 vertices there are more possibilities than atoms in the universe.

AI can explore this space far more aggressively than humans.

3. It shows AI can assist pure mathematics

Similar to:

  • AlphaGo (games)

  • AlphaFold (biology)

AlphaEvolve suggests AI may become a tool for discovering new mathematical objects.


In simple terms:

The significance is that an AI system discovered better examples of large pattern-avoiding graphs, which pushed forward the known limits of several Ramsey numbers—something mathematicians had struggled to improve for years.


If you're interested, I can also explain how the AI actually searches the graph space (it’s a fascinating mix of evolutionary algorithms + combinatorics + SAT solving).

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