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Ticket #1716 (assigned defect)

Opened 9 years ago

Last modified 4 years ago

Obtaining incorrect results under cygwin build of PICO

Reported by: jwatson Owned by: pico-developers
Priority: normal Milestone: Acro [wish list]
Component: PICO Version: PICO 1.2.1
Keywords: Cc: jeckstei@…
Subcomponent: Source Code

Description (last modified by wehart) (diff)

I've attached (hopefully) test.mod and test.dat which can be run through AMPL;
cplex output from snuffles is attached as well (cplex.out). Under CPLEX, you
get an incumbent of about 195K - dollars, so this is minimization - in about
50-ish B&B nodes. I terminated it early, as the proof takes over 24 hours.
However, under cygwin with AMPL and PICO, AMPL terminates quite early - in a
few minutes - with an incumbent of 955522.56. Which is clearly greater than
195K. I didn't set any PICO options, so I assume this means PICO thinks it has
found/proved the optimal.

Attachments

bug.tar Download (163.0 KB) - added by jwatson 9 years ago.
Tar-ball containing ampl model/data files and cplex output

Change History

Changed 9 years ago by jwatson

Tar-ball containing ampl model/data files and cplex output

comment:1 Changed 8 years ago by wehart

  • Owner changed from pico-developers to wehart
  • op_sys changed from Windows XP to Windows

WEH: I'm going to look at this bug. I think this needs to be resolved for the PICO release.

comment:2 Changed 8 years ago by wehart

  • Cc jeckstei added
  • Priority changed from high to lowest
  • severity changed from blocker to normal

WEH: I've confirmed this behavior. However, there are two sets of integer variables that are unbounded. I suspect that this isn't so much a PICO bug, as a difference in how PICO and CPLEX are interpretting unbounded integer values.

I've tried treating these unbounded values as binary values, as we've done with other test problems, but the problem then becomes infeasible.

I'm reducing the severity of this bug, given that I don't think that this represents a true bug in PICO. However, I'm setting this to have high priority because this sort of discrepancy with CPLEX seems problematic. In this case, I can't yet isolate it.

comment:3 Changed 6 years ago by wehart

  • Version changed from Beta to PICO 1.2.1
  • Description modified (diff)
  • Milestone set to PICO 1.3

comment:4 Changed 6 years ago by jdsiiro

  • Priority changed from lowest to normal
  • severity normal deleted

Converting all severities into priorities and deprecating the severity field.

comment:5 Changed 5 years ago by caphill

  • Milestone changed from PICO 1.3 to PICO 1.4

comment:6 Changed 4 years ago by jdsiiro

  • Milestone changed from PICO 1.4 to Acro [wish list]

comment:7 Changed 4 years ago by wehart

  • Owner changed from wehart to pico-developers
  • Status changed from new to assigned

I can't resolve this, since Cygwin doesn't work on my PC. :(

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