diff -r d8305c9b6fdf -r f7b87d84864d src/bisection_tree/btfn.rs
--- a/src/bisection_tree/btfn.rs	Sat Dec 21 23:32:20 2024 -0500
+++ b/src/bisection_tree/btfn.rs	Sun Dec 22 14:54:46 2024 -0500
@@ -505,7 +505,7 @@
 ///
 /// `U` is the domain, generally [`Loc`]`<F, N>`, and `F` the type of floating point numbers.
 /// `Self` is generally a set of `U`, for example, [`Cube`]`<F, N>`.
-pub trait P2Minimise<U, F : Float> : Set<U> {
+pub trait P2Minimise<U : Space, F : Float> : Set<U> {
     /// Minimise `g` over the set presented by `Self`.
     ///
     /// The function returns `(x, v)` where `x` is the minimiser `v` an approximation of `g(x)`.