[Scip] XOR constraints

[Stefan Heinz]

Hi Jörg,

an xor(x_1, ..., x_n) is usually not equivalent to x_1 + x_2 + ... + x_n 
<= 1. This is only the case for n = 2. An xor is satisfied if an odd 
number of the variables is set to true. I just check the code. even in 
the special case of n = 2, SCIP does not upgrade the xor constraint into 
an (linear) variable bound constraint (cons_varbound.c). That is 
something we could thing about.

Best Stefan

On 10/17/11 22:16, Jörg Pfähler wrote:
> Hi,
>
> does SCIP somehow take advantage of an xor-constraint (only one of the binary
> variables x_1, ..., x_k is 1) created with SCIPcreateConsXor instead of
> creating an equivalent constraint (x_1 + ... + x_k<= 1) with
> SCIPcreateConsLinear?
>
> Best Regards,
> Jörg
>
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