Benoît Legat

Thanks to https://github.com/jump-dev/MathOptInterface.jl/pull/2194

Riemannian black box function with JuMP/MOI

7

```julia """ struct RiemannianFirstOrderFunction{F,G}

See https://github.com/JuliaManifolds/Manopt.jl/pull/264#pullrequestreview-1713936091

Non-array manifold with JuMP/MOI

2

In JuMP, we only define array-shaped points in manifold but as mentioned, e.g., in https://github.com/JuliaManifolds/Manopt.jl/pull/264#issuecomment-1600473005, for `FixedRankMatrices` they could also be represented by their SVD. We should make this work:...

Some draft I started but didn't finish

If no solver is provided, we fall back to a representation conversion: https://github.com/JuliaPolyhedra/Polyhedra.jl/blob/3e5e93490e7f2558263df3cca4432e722e761cb2/src/redundancy.jl#L106-L112 We should use a LU decomposition instead

We shouldn't have `_show` for printing monomials as its makes it hard to redefine it to custom printing.

Closes https://github.com/JuliaAlgebra/MultivariatePolynomials.jl/issues/277