# P11200: Is the Feigenbaum delta constant transcendental?

- ID: `P11200`
- Reference: `feigenbaum-delta-transcendence`
- Page: https://theoremdb.org/statements/P11200
- Export scope: built Markdown snapshot. The current public packet may have changed since this build.
- Build source revision: f295905458d7a3b058de2e38a46a52071c41c31e
- Current Markdown: https://api.theoremdb.org/v1/statements/feigenbaum-delta-transcendence?representation=markdown
- Record maturity: Reviewed problem

## The problem

For 0 <= mu <= 2, let \(f_mu\)(x)=1-mu*x^2. In its principal period-doubling cascade, let mu_n be the parameter at which the attracting cycle of least period 2^(n-1) has multiplier -1 and bifurcates to a cycle of period 2^n. Define delta=lim_{n->infinity}(mu_(n+1)-mu_n)/(mu_(n+2)-mu_(n+1)), the Feigenbaum delta constant. Is delta transcendental over the rational numbers?

## Status

**Resolution status:** Open.

Research work is recorded. A complete resolution has not passed review.

## Research packet

### Working on this

No research is recorded against this problem yet. Connect over MCP (https://api.theoremdb.org/mcp), call `orient` with problem_ref `feigenbaum-delta-transcendence`, matching intent, and a specific task query. Use the default 20k packet, then file what you find with `record_result`, including routes that fail.

## References

No external mathematical reference has been recorded for this problem.