Opened 9 years ago

Closed 9 years ago

# Inequalities in MixedIntegerLinearProgram are not properly handled

Reported by: Owned by: ppurka ncohen major sage-duplicate/invalid/wontfix linear programming MixedIntegerLinearProgram LinearConstraint LinearFunction dimpase Dmitrii Pasechnik, Punarbasu Purkayastha N/A

### Description

The `<=` and `>=` inequalities are not properly handled in `MixedIntegerLinearProgram` - essentially in both `sage.numerical.mip.LinearConstraint` and `sage.numerical.mip.LinearFunction`. Here is an example:

```sage: p = MixedIntegerLinearProgram()
sage: b = p.new_variable()
sage: b[0] <= b[1] <= 2  # This is not ok
x_1 <= 2
sage: (b[0] <= b[1] <= 2).constraints # Not ok
[x_1, 2]
sage: b[0] >= b[1] # This is ok
x_1 <= x_0
sage: 1 >= b[1]    # This is not since it starts with a constant
False
sage: 1 >= b[1] >= 2*b[0] # Not ok
False
sage: b[2] >= b[1] >= 2*b[0]  # Not ok
2 x_0 <= x_1
```

### comment:1 Changed 9 years ago by dimpase

• Status changed from new to needs_review

this is a duplicate of #12091, right?

### comment:2 follow-up: ↓ 3 Changed 9 years ago by ppurka

This is dupe of #12091. Please close. I don't see the option to close tickets. ( I got no powers :'( )

### comment:3 in reply to: ↑ 2 Changed 9 years ago by dimpase

• Status changed from needs_review to positive_review

This is dupe of #12091. Please close. I don't see the option to close tickets. ( I got no powers :'( )

Me neither, but we can positively review it to its quick and painless demise.

Hoogedelgeleerde Release Manager, AUB, dit is een dupe...

### comment:4 follow-up: ↓ 5 Changed 9 years ago by ncohen

• Milestone changed from sage-5.0 to sage-duplicate/invalid/wontfix

This + "positive review" is the standard incantation `:-)`

Nathann

### comment:5 in reply to: ↑ 4 ; follow-up: ↓ 6 Changed 9 years ago by dimpase

This + "positive review" is the standard incantation `:-)`

Nathann

natuurlijk, als u nu in Brussel woont, moet u ook de laatste woord, "dupe", ofwel "slachtoffer", kennen :)

### comment:6 in reply to: ↑ 5 Changed 9 years ago by ncohen

natuurlijk, als u nu in Brussel woont, moet u ook de laatste woord, "dupe", ofwel "slachtoffer", kennen :)

My god. This last incantation is not in my book. Hopefully Jeroen will understand `:-D`

Nathann

### comment:7 Changed 9 years ago by jdemeyer

• Resolution set to duplicate
• Reviewers set to Dmitrii Pasechnik, Punarbasu Purkayastha
• Status changed from positive_review to closed
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