1 files changed, 64 insertions, 0 deletions

diff --git a/subprojects/store-reasoning/src/main/java/tools/refinery/store/reasoning/translator/multiobject/EqualsRefiner.java b/subprojects/store-reasoning/src/main/java/tools/refinery/store/reasoning/translator/multiobject/EqualsRefiner.java
new file mode 100644
index 00000000..d8db4ec4
--- /dev/null
+++ b/subprojects/store-reasoning/src/main/java/tools/refinery/store/reasoning/translator/multiobject/EqualsRefiner.java
@@ -0,0 +1,64 @@
+/*
+ * SPDX-FileCopyrightText: 2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package tools.refinery.store.reasoning.translator.multiobject;
+
+import tools.refinery.store.model.Interpretation;
+import tools.refinery.store.reasoning.ReasoningAdapter;
+import tools.refinery.store.reasoning.refinement.AbstractPartialInterpretationRefiner;
+import tools.refinery.store.reasoning.representation.PartialSymbol;
+import tools.refinery.store.representation.Symbol;
+import tools.refinery.store.representation.TruthValue;
+import tools.refinery.store.representation.cardinality.CardinalityInterval;
+import tools.refinery.store.representation.cardinality.CardinalityIntervals;
+import tools.refinery.store.tuple.Tuple;
+
+public class EqualsRefiner extends AbstractPartialInterpretationRefiner<TruthValue, Boolean> {
+        private final Interpretation<CardinalityInterval> countInterpretation;
+
+        private EqualsRefiner(ReasoningAdapter adapter, PartialSymbol<TruthValue, Boolean> partialSymbol,
+                          Symbol<CardinalityInterval> countSymbol) {
+                super(adapter, partialSymbol);
+                countInterpretation = adapter.getModel().getInterpretation(countSymbol);
+        }
+
+        @Override
+        public boolean merge(Tuple key, TruthValue value) {
+                if (value == TruthValue.UNKNOWN) {
+                        return true;
+                }
+                if (value == TruthValue.ERROR) {
+                        return false;
+                }
+                int left = key.get(0);
+                int right = key.get(1);
+                boolean isDiagonal = left == right;
+                if (isDiagonal && value == TruthValue.FALSE) {
+                        return false;
+                }
+                if (!isDiagonal) {
+                        return !value.may();
+                }
+                if (value != TruthValue.TRUE) {
+                        throw new IllegalArgumentException("Unknown TruthValue: " + value);
+                }
+                // {@code isDiagonal} is true, so this could be {@code left} or {@code right}.
+                var unaryKey = Tuple.of(left);
+                var currentCount = countInterpretation.get(unaryKey);
+                if (currentCount == null) {
+                        return false;
+                }
+                var newCount = currentCount.meet(CardinalityIntervals.LONE);
+                if (newCount.isEmpty()) {
+                        return false;
+                }
+                countInterpretation.put(unaryKey, newCount);
+                return true;
+        }
+
+        public static Factory<TruthValue, Boolean> of(Symbol<CardinalityInterval> countSymbol) {
+                return (adapter, partialSymbol) -> new EqualsRefiner(adapter, partialSymbol, countSymbol);
+        }
+}