# It there a way or package to solve the nonlinear mixed complementarity problem?

**URL:** https://discourse.julialang.org/t/it-there-a-way-or-package-to-solve-the-nonlinear-mixed-complementarity-problem/51161
**Category:** Optimization (Mathematical)
**Tags:** jump
**Created:** [December 3, 2020, 1:42am UTC](https://discourse.julialang.org/t/it-there-a-way-or-package-to-solve-the-nonlinear-mixed-complementarity-problem/51161 "2020-12-03T01:42:13Z")
**Posts on this page:** 3
**Page:** 1

<div class="post-metadata">

### Author: ![jshengdb](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jshengdb/32/21238_2.png) [@jshengdb](https://discourse.julialang.org/u/jshengdb)
#### Post date: [December 3, 2020, 1:42am UTC](https://discourse.julialang.org/t/it-there-a-way-or-package-to-solve-the-nonlinear-mixed-complementarity-problem/51161/1 "2020-12-03T01:42:13Z")

</div>

Hi Julia user:

I was wondering if there was a way or package to model and solver the nonlinear mixed complementarity problem? I know now we can model the linear complementarity problem by using complement constraints in JuMP and solve it through PATH.jl [https://github.com/odow/PATH.jl](https://github.com/odow/PATH.jl)

However, I tried to model a nonlinear complementarity constraint using MOI.complements but it reports the error  
"MOI.Complements` constraints are not supported and cannot be bridged into supported constrained variables and constraints. "

I am just curious if I should claim the constraint as a nonlinear complementarity (like using NLconstraint instead of constraint in optimization problem)? But I couldn’t find any related information in JuMP v0.21.5 document on this.

Any suggestions? Thanks.

---

<div class="post-metadata">

### 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 3, 2020, 2:30am UTC](https://discourse.julialang.org/t/it-there-a-way-or-package-to-solve-the-nonlinear-mixed-complementarity-problem/51161/2 "2020-12-03T02:30:11Z")

</div>

Nonlinear complementarity constraints are not supported: [https://github.com/jump-dev/JuMP.jl/issues/2308](https://github.com/jump-dev/JuMP.jl/issues/2308)

As you suggest, you should manually reformulate your problem into the nonlinear equivalent.

---

<div class="post-metadata">

### Author: ![jshengdb](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jshengdb/32/21238_2.png) [@jshengdb](https://discourse.julialang.org/u/jshengdb)
#### Post date: [December 3, 2020, 2:38am UTC](https://discourse.julialang.org/t/it-there-a-way-or-package-to-solve-the-nonlinear-mixed-complementarity-problem/51161/3 "2020-12-03T02:38:35Z")

</div>

Thanks for the reply here.