# nLab seven trees in one

Seven trees in one

# Seven trees in one

## Idea

There is a natural bijection between the set of finite binary trees and the set of seven-tuples of such.

This observation, originally made by Bill Lawvere, has since then been expanded to other “polynomial equations” apart from $T \simeq T^7$ and other types than trees, revealing connections between type theory and calculus.

## References

Last revised on June 1, 2021 at 12:14:21. See the history of this page for a list of all contributions to it.