gation of
the integer variable at index -i -1 or to NOT the literal at the same index.
Ex: A variable index 4 will refer to the integer variable model.variables(4)
and an index of -5 will refer to the negation of the same variable. A literal
index 4 will refer to the logical fact that model.variable(4) == 1 and a
literal index of -5 will refer to the logical fact model.variable(4) == 0.
</pre><p>Protobuf type</p><div class="fragment"><div class="line">operations_research.sat.IntegerVariableProto </div>
</di