1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
|
package hu.bme.mit.inf.dslreasoner.viatrasolver.logic2viatra.cardinality
import com.google.common.collect.ImmutableList
import com.google.common.collect.ImmutableMap
import hu.bme.mit.inf.dslreasoner.ilp.cbc.CbcResult
import hu.bme.mit.inf.dslreasoner.ilp.cbc.CbcSolver
import java.util.HashSet
import java.util.List
import java.util.Map
import java.util.Set
import org.eclipse.xtend.lib.annotations.FinalFieldsConstructor
@FinalFieldsConstructor
class CbcPolyhedronSolver implements PolyhedronSolver {
val boolean lpRelaxation
val double timeoutSeconds
val boolean silent
new() {
this(false, -1, true)
}
override createSaturationOperator(Polyhedron polyhedron) {
new CbcSaturationOperator(polyhedron, lpRelaxation, timeoutSeconds, silent)
}
}
class CbcSaturationOperator extends AbstractPolyhedronSaturationOperator {
val boolean lpRelaxation
val double timeoutSeconds
val boolean silent
val double[] columnLowerBounds
val double[] columnUpperBounds
val double[] objective
val Map<Dimension, Integer> dimensionsToIndicesMap
new(Polyhedron polyhedron, boolean lpRelaxation, double timeoutSeconds, boolean silent) {
super(polyhedron)
this.lpRelaxation = lpRelaxation
this.timeoutSeconds = timeoutSeconds
this.silent = silent
val numDimensions = polyhedron.dimensions.size
columnLowerBounds = newDoubleArrayOfSize(numDimensions)
columnUpperBounds = newDoubleArrayOfSize(numDimensions)
objective = newDoubleArrayOfSize(numDimensions)
dimensionsToIndicesMap = ImmutableMap.copyOf(polyhedron.dimensions.indexed.toMap([value], [key]))
}
override doSaturate() {
val numDimensions = polyhedron.dimensions.size
for (var int j = 0; j < numDimensions; j++) {
val dimension = polyhedron.dimensions.get(j)
columnLowerBounds.set(j, dimension.lowerBound.toDouble(Double.NEGATIVE_INFINITY))
columnUpperBounds.set(j, dimension.upperBound.toDouble(Double.POSITIVE_INFINITY))
}
val constraints = nonTrivialConstraints
val numConstraints = constraints.size
val rowStarts = newIntArrayOfSize(numConstraints + 1)
val rowLowerBounds = newDoubleArrayOfSize(numConstraints)
val rowUpperBounds = newDoubleArrayOfSize(numConstraints)
val numEntries = constraints.map[coefficients.size].reduce[a, b|a + b] ?: 0
rowStarts.set(numConstraints, numEntries)
val columnIndices = newIntArrayOfSize(numEntries)
val entries = newDoubleArrayOfSize(numEntries)
val unconstrainedDimensions = new HashSet
for (dimension : polyhedron.dimensions) {
if (dimension.lowerBound === null && dimension.upperBound === null) {
unconstrainedDimensions += dimension
}
}
var int index = 0
for (var int i = 0; i < numConstraints; i++) {
rowStarts.set(i, index)
val constraint = constraints.get(i)
rowLowerBounds.set(i, constraint.lowerBound.toDouble(Double.NEGATIVE_INFINITY))
rowUpperBounds.set(i, constraint.upperBound.toDouble(Double.POSITIVE_INFINITY))
if (!dimensionsToIndicesMap.keySet.containsAll(constraint.coefficients.keySet)) {
throw new IllegalArgumentException("Constrains has unknown dimensions")
}
for (var int j = 0; j < numDimensions; j++) {
val dimension = polyhedron.dimensions.get(j)
val coefficient = constraint.coefficients.get(dimension)
if (coefficient !== null && coefficient != 0) {
unconstrainedDimensions -= dimension
columnIndices.set(index, j)
entries.set(index, coefficient)
index++
}
}
}
if (index != numEntries) {
throw new AssertionError("Last entry does not equal the number of entries in the constraint matrix")
}
for (expressionToSaturate : polyhedron.expressionsToSaturate) {
val result = saturate(expressionToSaturate, rowStarts, columnIndices, entries, rowLowerBounds,
rowUpperBounds, unconstrainedDimensions, constraints)
if (result != PolyhedronSaturationResult.SATURATED) {
return result
}
}
PolyhedronSaturationResult.SATURATED
}
protected def saturate(LinearBoundedExpression expressionToSaturate, int[] rowStarts, int[] columnIndices,
double[] entries, double[] rowLowerBounds, double[] rowUpperBounds, Set<Dimension> unconstrainedDimensions,
ImmutableList<LinearConstraint> constraints) {
val numDimensions = objective.size
for (var int j = 0; j < numDimensions; j++) {
objective.set(j, 0)
}
switch (expressionToSaturate) {
Dimension: {
// CBC will return nonsensical results or call free() with invalid arguments if
// it is passed a fully unconstrained (-Inf lower and +Int upper bound, no inequalities) variable
// in the objective function.
if (unconstrainedDimensions.contains(expressionToSaturate)) {
return PolyhedronSaturationResult.SATURATED
}
val j = getIndex(expressionToSaturate)
objective.set(j, 1)
}
LinearConstraint: {
for (pair : expressionToSaturate.coefficients.entrySet) {
val dimension = pair.key
// We also have to check for unconstrained dimensions here to avoid crashing.
if (unconstrainedDimensions.contains(dimension)) {
expressionToSaturate.lowerBound = null
expressionToSaturate.upperBound = null
return PolyhedronSaturationResult.SATURATED
}
val j = getIndex(dimension)
objective.set(j, pair.value)
}
}
default:
throw new IllegalArgumentException("Unknown expression: " + expressionToSaturate)
}
val minimizationResult = CbcSolver.solve(columnLowerBounds, columnUpperBounds, rowStarts, columnIndices,
entries, rowLowerBounds, rowUpperBounds, objective, lpRelaxation, timeoutSeconds, silent)
switch (minimizationResult) {
CbcResult.SolutionBounded: {
val value = Math.floor(minimizationResult.value)
expressionToSaturate.lowerBound = value as int
setBound(expressionToSaturate, constraints, value, columnLowerBounds, rowLowerBounds)
}
case CbcResult.SOLUTION_UNBOUNDED: {
expressionToSaturate.lowerBound = null
setBound(expressionToSaturate, constraints, Double.NEGATIVE_INFINITY, columnLowerBounds, rowLowerBounds)
}
case CbcResult.UNSAT:
return PolyhedronSaturationResult.EMPTY
case CbcResult.ABANDONED,
case CbcResult.TIMEOUT:
return PolyhedronSaturationResult.UNKNOWN
default:
throw new RuntimeException("Unknown CbcResult: " + minimizationResult)
}
for (var int j = 0; j < numDimensions; j++) {
val objectiveCoefficient = objective.get(j)
objective.set(j, -objectiveCoefficient)
}
val maximizationResult = CbcSolver.solve(columnLowerBounds, columnUpperBounds, rowStarts, columnIndices,
entries, rowLowerBounds, rowUpperBounds, objective, lpRelaxation, timeoutSeconds, silent)
switch (maximizationResult) {
CbcResult.SolutionBounded: {
val value = Math.ceil(-maximizationResult.value)
expressionToSaturate.upperBound = value as int
setBound(expressionToSaturate, constraints, value, columnUpperBounds, rowUpperBounds)
}
case CbcResult.SOLUTION_UNBOUNDED: {
expressionToSaturate.upperBound = null
setBound(expressionToSaturate, constraints, Double.POSITIVE_INFINITY, columnUpperBounds, rowUpperBounds)
}
case CbcResult.UNSAT:
throw new RuntimeException("Minimization was SAT, but maximization is UNSAT")
case CbcResult.ABANDONED,
case CbcResult.TIMEOUT:
return PolyhedronSaturationResult.UNKNOWN
default:
throw new RuntimeException("Unknown CbcResult: " + maximizationResult)
}
return PolyhedronSaturationResult.SATURATED
}
private def toDouble(Integer nullableInt, double defaultValue) {
if (nullableInt === null) {
defaultValue
} else {
nullableInt.doubleValue
}
}
private def int getIndex(Dimension dimension) {
val index = dimensionsToIndicesMap.get(dimension)
if (index === null) {
throw new IllegalArgumentException("Unknown dimension: " + dimension)
}
index
}
private def void setBound(LinearBoundedExpression expression, List<LinearConstraint> constraints, double bound,
double[] columnBounds, double[] rowBounds) {
switch (expression) {
Dimension: {
val j = getIndex(expression)
columnBounds.set(j, bound)
}
LinearConstraint: {
val i = constraints.indexOf(expression)
if (i >= 0) {
rowBounds.set(i, bound)
}
}
}
}
}
|
