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[GeneralDichotomy] handle no solution case #207

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[GeneralDichotomy] handle no solution case #207

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10 changes: 4 additions & 6 deletions ext/Polyhedra/GeneralDichotomy.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -24,9 +24,8 @@ function MOA.minimize_multiobjective!(
# Storage we need for the algorithm.
weights, solutions = Weight[], MOA.SolutionPoint[]
n_obj = MOI.output_dimension(model.f)
# First, minimize the first objective to obtain a primal feasible point.
w = zeros(Float64, n_obj)
w[1] = 1.0
# First, minimize the combined objectives to obtain a primal feasible point.
w = ones(Float64, n_obj)

@odow odow Jul 1, 2026

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Suggested change
w = ones(Float64, n_obj)
w = fill(1 / n_obj, n_obj)

Does it matter?

status, solution = MOA._solve_weighted_sum(model, alg, w)
if solution === nothing
return status, nothing
Expand All @@ -40,7 +39,7 @@ function MOA.minimize_multiobjective!(
w[i] = 1.0
z = w' * solution.y
adj_bnd = Int[-j for j in 1:n_obj if j != i]
push!(weights, Weight(w, z, adj_bnd, [1], i == 1, false))
push!(weights, Weight(w, z, adj_bnd, [1], false, false))
end
# Prevent solution duplicates: existing_sol maps an rounded objective vector
# to its index in `solutions::Vector{MOA.SolutionPoint}`.
Expand All @@ -59,8 +58,7 @@ function MOA.minimize_multiobjective!(
end
status, sol = MOA._solve_weighted_sum(model, alg, weight.w)
if sol === nothing
# TODO(odow): what to do when this solve fails?
return status, solutions
return MOI.NUMERICAL_ERROR, solutions
end
weight.tested = true
if !haskey(existing_sol, _round(sol.y; atol))
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