Levit–Mandrescu Unimodality Conjecture
A graph on vertices is very well-covered if every maximal independent set has size . Levit and Mandrescu conjectured that the independence polynomial of every very well-covered graph is unimodal, i.e. its coefficient sequence is nondecreasing and then nonincreasing.
- Result
- Disproved
- Status
- Resolved
- AI contribution
- AI-discovered
- Method
- Construction
- Field
- Graph Theory, Independence Polynomials
- Posed by
- Vadim E. Levit, Eugen Mandrescu
- Year posed
- 2006
- Years open
- 20y
- Solved
- 2026-07-22
- Model
- GPT-5.6 Sol, Claude Fable 5
- Vendor
- —
- Collaborators
- Lucas B.
- Verification
- Unreviewed
- Publication
- Announced
- Significance
- 10 / 100
- Disclosed cost
- —
- Wikipedia
- No dedicated article
What the AI did
The models produced an explicit counterexample: the whiskering of , a very well-covered graph on 4,074 vertices, whose independence polynomial has a strict local valley at . Per the announcement, the search took a few hours once the question was posed.
Verification
Announced on LinkedIn by Lucas B. (Head of AI Research, Jump Trading); no preprint yet, and the reviewers credited are internal to the team rather than independent. The stated polynomial was recomputed with exact integer arithmetic: holds, so the polynomial given is genuinely not unimodal, and its low-order coefficients (, ) are consistent with a graph on 4,074 vertices. What remains unchecked is that the whiskered graph's independence polynomial equals the polynomial stated.
Source
- AnnouncementLucas B. (Jump Trading), LinkedIn announcement
Submitted by Rasmus Lindahl on