# Error processing constraint

**URL:** <https://discuss.ampl.com/t/error-processing-constraint/965>\
**Category:** Support\
**Created:** [February 26, 2024, 8:25pm UTC](https://discuss.ampl.com/t/error-processing-constraint/965 "2024-02-26T20:25:50Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Steph](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.ampl.com/steph/32/671_2.png) [@Steph](https://discuss.ampl.com/u/Steph)\
**Post date:** [February 26, 2024, 8:25pm UTC](https://discuss.ampl.com/t/error-processing-constraint/965/1 "2024-02-26T20:25:50Z")

</div>

I am declaring the following restriction:  
subject to Siembra\_Cult\_perm1 {j in PERM, k in U, t in T}:  
z [j,k,t+fen[j]] \<= 1 + 1000\*(z[j,k,t]-1);

however, t + fen[j] is greater than T, so I get the following:

Error executing “solve” command:  
error processing constraint Siembra\_Cult\_perm1[12,1,10]:  
invalid subscript z[12,1,13]

 ![image](https://us1.discourse-cdn.com/flex019/uploads/ampl/original/1X/64a5b76b4189aed2a0f1803c5289a05acbbc7abf.png)

---

<div class="post-metadata">

**Author:** ![gomfy](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.ampl.com/gomfy/32/103_2.png) [@gomfy](https://discuss.ampl.com/u/gomfy)\
**Post date:** [March 7, 2024, 7:56pm UTC](https://discuss.ampl.com/t/error-processing-constraint/965/2 "2024-03-07T19:56:35Z")

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Hello Steph,

You can add a filter to your indexing expression as follows:

```ampl
subject to Siembra_Cult_perm1 {j in PERM, k in U, t in T: t + fen[j] <= T}:
z [j,k,t+fen[j]] <= 1 + 1000*(z[j,k,t]-1);

```

Make sure to double check that this will give you the correct constraints. You can look at your constraints explicitly by saying:

```ampl
expand Siembra_Cult_perm1;

```