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<div class="moz-cite-prefix">James,<br>
<br>
It is not a bug in Cbc, but an error (feature?) in Coin's lp
format reader. The reader does not like the last two constraints
- if I replace<br>
<br>
<i>p0_2 + p1_2 = x2</i><i><br>
</i><i>p0_3 + p1_3 = x3<br>
<br>
by<br>
<br>
</i><i> </i><i>p0_2 + p1_2 - x2 = 0</i><i><br>
</i><i>p0_3 + p1_3 - x3</i><i> = 0<br>
<br>
everything is fine<br>
<br>
John Forrest<br>
</i><br>
<br>
On 08/05/15 09:07, James Gunning wrote:<br>
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<blockquote cite="mid:554C6EB5.9000205@csiro.au" type="cite">
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Hello All,<br>
This is probably a dumb question: why does this simple .lp
file<br>
<br>
<i>Min</i><i><br>
</i><i>obj: -10.9139 p1_3 +15.3211 x1 -3.30662 x3 </i><i><br>
</i><i>s.t.</i><i><br>
</i><i>x0 - p0_2 >= 0</i><i><br>
</i><i>x2 - p0_2 >= 0</i><i><br>
</i><i>p0_2 - x0 - x2 >= -1</i><i><br>
</i><i>x0 - p0_3 >= 0</i><i><br>
</i><i>x3 - p0_3 >= 0</i><i><br>
</i><i>p0_3 - x0 - x3 >= -1</i><i><br>
</i><i>x1 - p1_2 >= 0</i><i><br>
</i><i>x2 - p1_2 >= 0</i><i><br>
</i><i>p1_2 - x1 - x2 >= -1</i><i><br>
</i><i>x1 - p1_3 >= 0</i><i><br>
</i><i>x3 - p1_3 >= 0</i><i><br>
</i><i>p1_3 - x1 - x3 >= -1</i><i><br>
</i><i>x0 + x1 = 1</i><i><br>
</i><i>x2 + x3 = 1</i><i><br>
</i><i>p0_2 + p1_2 = x2</i><i><br>
</i><i>p0_3 + p1_3 = x3</i><i><br>
</i><i>Binaries</i><i><br>
</i><i>x0 x1 x2 x3 p0_2 p0_3 p1_2 p1_3</i><i><br>
</i><i>End</i><br>
<br>
<br>
<br>
Give me "Integer infeasible..." under cbc?<br>
<br>
lp_solve gives me an integer solution <br>
<br>
p1_3 0<br>
x1 0<br>
x3 1<br>
x0 1<br>
p0_2 0<br>
x2 0<br>
p0_3 1<br>
p1_2 0<br>
<br>
<br>
<br>
I'm sure I've done something stupid, but it may be a subtle
roundoff thing?<br>
This is cbc 2.8.12.<br>
<br>
Best wishes all & kudos to John for keeping things going so
well...<br>
James.<br>
<br>
<br>
<br>
<br>
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<br>
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