SoftAllDifferent and SoftGCC incorrectly throw AssertionErrors on infeasible stores

[thomasleaute]

The following code:

Store store = new Store ();
		
// Create the variables
IntVar cost = new IntVar (store, "cost", 0, 2);
IntVar[] vars = new IntVar [2];
vars[0] = new IntVar (store, "v_0", 0, 1);
vars[1] = new IntVar (store, "v_1", 0, 1);

// Ground the variables using In constraints, such that the store is infeasible
store.impose(new In (cost, new IntervalDomain (0, 0)));
store.impose(new In (vars[0], new IntervalDomain (0, 0)));
store.impose(new In (vars[1], new IntervalDomain (0, 0)));
		
// Impose a SoftAlldifferent constraint
store.imposeDecomposition(new SoftAlldifferent (vars, cost, ViolationMeasure.DECOMPOSITION_BASED));
		
System.out.println(store.consistency());

throws

Exception in thread "main" java.lang.AssertionError: non-optimal arcs:
[1->sink, flow=0/1  reduced=-1, index=2]
	at org.jacop.constraints.netflow.Assert.checkOptimality(Assert.java:269)
	at org.jacop.constraints.netflow.simplex.NetworkSimplex.networkSimplex(NetworkSimplex.java:368)
	at org.jacop.constraints.netflow.NetworkFlow.consistency(NetworkFlow.java:255)
	at org.jacop.core.Store.consistency(Store.java:547)

when asserts are enabled.

[thomasleaute]

Same issue with SoftGCC:

Store store = new Store ();
		
// Create the variables
IntVar cost = new IntVar (store, "cost", 0, 2);
		
IntVar[] xVars = new IntVar[2];
xVars[0] = new IntVar (store, "x0", 0, 1);
xVars[1] = new IntVar (store, "x1", 0, 1);
		
IntVar[] hardCounters = new IntVar [2];
hardCounters[0] = new IntVar (store, "hardCounter0", 0, 2);
hardCounters[1] = new IntVar (store, "hardCounter1", 0, 2);
		
IntVar[] softCounters = new IntVar [2];
softCounters[0] = new IntVar (store, "softCounter0", 0, 2);
softCounters[1] = new IntVar (store, "softCounter1", 0, 2);
		
// Ground the variables using In constraints such that the store is infeasible
store.impose(new In (xVars[0], new IntervalDomain (0, 0)));
store.impose(new In (xVars[1], new IntervalDomain (0, 0)));
store.impose(new In (hardCounters[0], new IntervalDomain (2, 2)));
store.impose(new In (softCounters[0], new IntervalDomain (1, 1)));
store.impose(new In (softCounters[1], new IntervalDomain (2, 2)));
store.impose(new In (cost, new IntervalDomain (1, 1)));
		
// Impose a SoftGCC 
store.imposeDecomposition(new SoftGCC (xVars, hardCounters, softCounters, cost, ViolationMeasure.VALUE_BASED));
		
System.out.println(store.consistency());

throws:

Exception in thread "main" java.lang.AssertionError: non-optimal arcs:
[1->c_1, flow=0/2  reduced=-2, index=2, forward = true, companion = [offset = 0, xVar = hardCounter1}]]
	at org.jacop.constraints.netflow.Assert.checkOptimality(Assert.java:269)
	at org.jacop.constraints.netflow.simplex.NetworkSimplex.networkSimplex(NetworkSimplex.java:368)
	at org.jacop.constraints.netflow.NetworkFlow.consistency(NetworkFlow.java:255)
	at org.jacop.core.Store.consistency(Store.java:547)

[thomasleaute]

Still reproducible in JaCoP 4.10.0.