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28 lines
923 B
28 lines
923 B
# MIPLearn: Extensible Framework for Learning-Enhanced Mixed-Integer Optimization
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# Copyright (C) 2020-2021, UChicago Argonne, LLC. All rights reserved.
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# Released under the modified BSD license. See COPYING.md for more details.
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import logging
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from typing import Any
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from miplearn import InternalSolver
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from miplearn.solvers.gurobi import GurobiSolver
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logger = logging.getLogger(__name__)
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def test_lazy_cb() -> None:
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solver = GurobiSolver()
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instance = solver.build_test_instance_knapsack()
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model = instance.to_model()
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def lazy_cb(cb_solver: InternalSolver, cb_model: Any) -> None:
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cobj = (cb_model.getVarByName("x[0]") * 1.0, "<", 0.0, "cut")
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if not cb_solver.is_constraint_satisfied(cobj):
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cb_solver.add_constraint(cobj)
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solver.set_instance(instance, model)
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solver.solve(lazy_cb=lazy_cb)
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solution = solver.get_solution()
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assert solution["x[0]"] == 0.0
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