")
end
m = JuMP.read_from_file(ARGS[1])
set_optimizer(m, Cbc.Optimizer)
optimize!(m)
@show JuMP.primal_status(m)
if JuMP.primal_status(m) == MOI.FEASIBLE_POINT
@show JuMP.objective_value(m)
end
```
JuMP is version 0.21.1 and Cbc.jl is version 0.6.6.
Both the files return that the model is infeasible:
```julia
Welcome to the CBC MILP Solver
Version: 2.10.3
Build Date: Oct 7 2019
command line - Cbc_C_Interface -solve -quit (default strategy 1)
** Current model not valid
Total time (CPU seconds): 0.00 (Wallclock seconds): 0.00
JuMP.primal_status(m) = NO_SOLUTION::ResultStatusCode = 0
```
But this seem to happen because they think the model is not valid?
If I just run cbc directly over the “.lp” file I get:
```julia
Welcome to the CBC MILP Solver
Version: 2.10.3
Build Date: Jun 15 2019
command line - cbc ../../test/Cbc_false_infeasible.mps (default strategy 1)
At line 1 NAME
At line 2 ROWS
At line 8 COLUMNS
At line 9 RHS
At line 14 RANGES
At line 15 BOUNDS
At line 16 ENDATA
Problem no_name has 4 rows, 0 columns and 0 elements
Coin0008I no_name read with 0 errors
Empty problem - 4 rows, 0 columns and 0 elements
Optimal - objective value 0
Optimal objective 0 - 0 iterations time 0.002
Total time (CPU seconds): 0.00 (Wallclock seconds): 0.00
```
Other solvers give the correct (zero-valued) feasible solution. Only Cbc fails at this test of mine.
---
### Author:  [@odow](https://discourse.julialang.org/u/odow)
#### Post date: [February 21, 2020, 9:32pm UTC](https://discourse.julialang.org/t/bug-jump-read-from-file-cbc-gives-infeasible-just-cbc-gives-feasible/34990/2 "2020-02-21T21:32:26Z")
Reading from file is not saying the model is infeasible. It says there is no solution because the model is invalid (look at the Cbc log).
This is a difference between cbc’s c interface and their lp file reader. I don’t think it’s a bug. I would say it’s expected behavior.
---
### Author:  [@Henrique\_Becker](https://discourse.julialang.org/u/Henrique_Becker)
#### Post date: [February 22, 2020, 2:02am UTC](https://discourse.julialang.org/t/bug-jump-read-from-file-cbc-gives-infeasible-just-cbc-gives-feasible/34990/3 "2020-02-22T02:02:03Z")
Ok… but should this happen if the model is built in JuMP?
```julia
#!/usr/bin/env julia --project=@.
using JuMP, Cbc
m = Model(Cbc.Optimizer)
empty_terms = AffExpr()
@constraint(m, empty_terms <= 2)
optimize!(m)
@show JuMP.primal_status(m)
if JuMP.primal_status(m) == MOI.FEASIBLE_POINT
@show JuMP.objective_value(m)
end
```
Also gives:
```julia
Welcome to the CBC MILP Solver
Version: 2.10.3
Build Date: Oct 7 2019
command line - Cbc_C_Interface -solve -quit (default strategy 1)
** Current model not valid
Total time (CPU seconds): 0.00 (Wallclock seconds): 0.00
JuMP.primal_status(m) = NO_SOLUTION::ResultStatusCode = 0
```
Also, is it expected that for a solver (Cbc) the model above is “invalid” and gives `NO_SOLUTION::ResultStatusCode` and for another (GLPK) it says nothing about the model “invalidity” and gives the following output:
```julia
JuMP.primal_status(m) = FEASIBLE_POINT::ResultStatusCode = 1
JuMP.objective_value(m) = 0.0
```
Finally, there is a reason why the GLPK version takes 20 seconds, and the Cbc version takes about 4 minutes? The Cbc version has that much extra code to compile?
---
### Author:  [@odow](https://discourse.julialang.org/u/odow)
#### Post date: [February 22, 2020, 4:50am UTC](https://discourse.julialang.org/t/bug-jump-read-from-file-cbc-gives-infeasible-just-cbc-gives-feasible/34990/4 "2020-02-22T04:50:46Z")
This is all expected behavior.
Solvers have different semantics for weird constraints like the one you’re formulating.
No idea on the time difference. Is it compile time or run time? What happens if you run twice in the same Julia session?
Edit: also, check the termination status for cbc and glpk.