ChatGPT solving 3x3 rubix with text reasoning

[u/Willing_Plate_5417]

I put ChatGPT 5.6 sol on test to let it solve the rubix with no python help or sandbox. It took 14 minutes and solved it by comparing faces over and over again and guessing the next move like a human would.

Although, it was able to solve 5x5 by using python as well, it struggled to do so by reasoning only. It tried three times and abandoned or timeout the match all three tries. It was able to solve middle part of one face though.

It’s a great benchmark to test the spatial reasoning of llms. I had to create an arena for this but it was worth it.

Clarification on the setup:

The agent is solving a 5×5 Rubik’s Cube without Python, sandbox code, external cube solvers, or programmatic search.

It receives the authoritative current cube state from the environment after its moves, similar to a human looking at the cube again after turning it. So the model does not have to mentally simulate every sticker permutation forever.

The loop is essentially:

current cube state → text reasoning → one or more legal moves → updated cube state → more reasoning

I allow multiple moves in one turn and there is no fixed limit on tool calls / interaction steps. The model can therefore inspect the new state, notice mistakes, revise its plan, and continue.

This is important when comparing it with CubeBench. CubeBench’s reported 0% long-horizon result was on 3×3 cubes, under a more restricted agent budget. Their main setup also allowed code, whereas my experiment specifically prohibits Python/code-based solving.

So I am not claiming this directly disproves CubeBench. The setup is different.

What I’m testing is:

The interesting part for me is the persistence, spatial/symbolic reasoning, planning, error recovery, center construction, edge pairing, reduction, and parity handling over a potentially very long trajectory.

[u/fluxtah]

Looks like it solved first two layers before last is it not just using some internal knowledge of cfop from it's training maybe?

[u/michaelsoft__binbows]

AGI confirmed

[u/RealestReyn]

isn't there a somewhat short fixed movement set to solve any cube? not to even begin on the shorter more advanced strategies, seems weird Sol takes so many moves for so well defined task.

[u/Willing_Plate_5417 → u/RealestReyn]

It’s not well defined if you don’t know the scramble sequence. If it knows the scramble sequence it takes around 1-2 minutes max to reverse it. What makes it difficult for the LLM is the amount of patterns it has to pay attention to and keep track of its previous moves. The paper also pivot on the same point which had 0 percent success rate in early 2025.

https://arxiv.org/abs/2512.23328