Concrete minkowski difference for hyperrectangular sets

[mforets]

The implementation of concrete minkowski difference for polytopic sets can be specialized to axis-aligned (= hyperrectangular sets in our notation) sets.

Sketch:
since they are hyperrectangular sets => their directions are parallel

LazySets.jl/src/ConcreteOperations/minkowski_difference.jl

Line 36 in 9b50aad

P ~ Q = \\{z ∈ ℝⁿ: sᵢᵀz ≤ rᵢ - ρ(sᵢ,Q), i=1,...,N\\}.

the normal directions of P⊖Q are also axis aligned
it remains to evaluate rᵢ - ρ(sᵢ,Q) for all i
(assume that the hyperrectangles are centered to the origin => both are obtained iirc with radius_hyperrectangle(H, i))
moreover, we can have an early termination to check that the minkowski difference is empty by computing the pairs of right hand sides +ei and -ei for each i