# Solving Fixed-MILP Problem

**URL:** <https://discourse.julialang.org/t/solving-fixed-milp-problem/51749>\
**Category:** Optimization (Mathematical)\
**Created:** [December 13, 2020, 1:32am UTC](https://discourse.julialang.org/t/solving-fixed-milp-problem/51749 "2020-12-13T01:32:00Z")\
**Posts on this page:** 1\
**Showing post:** 4

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**Author:** ![odow](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/odow/32/28685_2.png) [@odow](https://discourse.julialang.org/u/odow)\
**Post date:** [December 13, 2020, 11:22pm UTC](https://discourse.julialang.org/t/solving-fixed-milp-problem/51749/4 "2020-12-13T23:22:49Z")

</div>

You’re looking for something like

```nohighlight
using JuMP, Cbc, Clp

function fix!(model::Model)
    solution = Dict(
        v => value(v) for v in all_variables(model)
    )
    for v in all_variables(model)
        if is_binary(v)
            unset_binary(v)
            fix(v, solution[v]; force = true)
        end
    end
    return
end

model = Model(Cbc.Optimizer)
@variable(model, x, Bin)
@objective(model, Max, 2 * x)
optimize!(model)
fix!(model)
set_optimizer(model, Clp.Optimizer)
optimize!(model)
dual(FixRef(x))

```

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