pyomo约束表示范围不等式表达式

Question

我是pyomo的菜鸟。我想这样做：

for w in ww:
    model.constraints.add(
        100 >= sum(8 * model.w[w, d, s] for d in dd for s in ss) >= 50
    )

相反，我尝试过这种方式：

for w in ww:
    model.constraints.add(
        100 >= sum(8 * model.w[w, d, s] for d in dd for s in ss)
    )

for w in ww:
    model.constraints.add(
        50 <= sum(8 * model.w[w, d, s] for d in dd for s in ss)
    )

但是没有用。它

WARNING: Loading a SolverResults object with a warning status into
    model=unknown;
        message from solver=<undefined>

我想念什么，你能告诉我什么吗？

Answer 1

已解决。我发现

WARNING: Loading a SolverResults object with a warning status into
    model=unknown;
        message from solver=<undefined>

因为该模型不可行。