# Variable declaration

**URL:** https://discourse.julialang.org/t/variable-declaration/44142
**Category:** Optimization (Mathematical)
**Tags:** jump
**Created:** [August 2, 2020, 5:29pm UTC](https://discourse.julialang.org/t/variable-declaration/44142 "2020-08-02T17:29:57Z")
**Posts on this page:** 3
**Page:** 1

<div class="post-metadata">

### Author: ![mamo](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mamo/32/25591_2.png) [@mamo](https://discourse.julialang.org/u/mamo)
#### Post date: [August 2, 2020, 5:29pm UTC](https://discourse.julialang.org/t/variable-declaration/44142/1 "2020-08-02T17:29:57Z")

</div>

Dear,  
send me some suggestion for a proper declaration of this variable  
@variable(model, CHANGE[k in FAMILY, l in FAMILY, j in UNITS, t in TIME, t1 in TIME: k\<\>l and t+1=t1], Bin)  
The problem is in k\<\>l (k must be different than l) and t+1=t1 (sequencing) - how is this properly stated in Julia/JuMP?  
Thank you!  
marco

---

<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: [August 2, 2020, 6:28pm UTC](https://discourse.julialang.org/t/variable-declaration/44142/2 "2020-08-02T18:28:10Z")

</div>

You need to use valid Julia syntax:

`(k != l) && (t + 1 == t1)`

---

<div class="post-metadata">

### Author: ![mamo](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mamo/32/25591_2.png) [@mamo](https://discourse.julialang.org/u/mamo)
#### Post date: [August 2, 2020, 6:50pm UTC](https://discourse.julialang.org/t/variable-declaration/44142/3 "2020-08-02T18:50:09Z")

</div>

Thank you odow.  
Regards,  
marco