diff --git a/domain/src/main/kotlin/ch/dissem/yaep/domain/GameCell.kt b/domain/src/main/kotlin/ch/dissem/yaep/domain/GameCell.kt
index 9b7b9e9..7e36c85 100644
--- a/domain/src/main/kotlin/ch/dissem/yaep/domain/GameCell.kt
+++ b/domain/src/main/kotlin/ch/dissem/yaep/domain/GameCell.kt
@@ -10,5 +10,6 @@ class GameCell<C : ItemClass<C>>(
 //    var selection by mutableStateOf(selection)
 //}
 
-fun <C : ItemClass<C>> GameCell<C>?.mayBe(item: Item<C>) =
-    this != null && (selection == item || (selection == null && options.contains(item)))
+fun <C : ItemClass<C>> GameCell<C>?.mayBe(item: Item<C>, mayHaveSelection: Boolean = true) =
+    this != null &&
+            ((mayHaveSelection && selection == item) || (selection == null && options.contains(item)))
diff --git a/domain/src/main/kotlin/ch/dissem/yaep/domain/clues.kt b/domain/src/main/kotlin/ch/dissem/yaep/domain/clues.kt
index 1f62b6b..efa90c5 100644
--- a/domain/src/main/kotlin/ch/dissem/yaep/domain/clues.kt
+++ b/domain/src/main/kotlin/ch/dissem/yaep/domain/clues.kt
@@ -114,9 +114,9 @@ class OrderClue<L : ItemClass<L>, R : ItemClass<R>>(val left: Item<L>, val right
 
         var removed = false
         try {
-            rowL.takeLast(rowL.size - lastR + 1)
+            rowL.takeLast(rowL.size - lastR)
                 .forEach { removed = it.options.remove(left) || removed }
-            rowR.take(firstL).forEach { removed = it.options.remove(right) || removed }
+            rowR.take(firstL + 1).forEach { removed = it.options.remove(right) || removed }
         } catch (e: IllegalArgumentException) {
             throw UnsolvablePuzzleException(e)
         }
@@ -216,7 +216,54 @@ class TripletClue<A : ItemClass<A>, B : ItemClass<B>, C : ItemClass<C>>(
     }
 
     override fun removeForbiddenOptions(grid: Grid): Boolean {
-        TODO("Not yet implemented")
+        val rowA = grid[aType.companion]
+        val rowB = grid[bType.companion]
+        val rowC = grid[cType.companion]
+
+        var removed = false
+
+        for (i in rowA.indices) {
+            val cellA = rowA[i]
+            if (cellA.mayBe(a, mayHaveSelection = false)) {
+                val cellBR = rowB.getOrNull(i + 1)
+                val cellCR = rowC.getOrNull(i + 2)
+                val cellBL = rowB.getOrNull(i - 1)
+                val cellCL = rowC.getOrNull(i - 2)
+
+                if (!(cellBR.mayBe(b) && cellCR.mayBe(c)) && !(cellBL.mayBe(b) && cellCL.mayBe(c))) {
+                    removed = cellA.options.remove(a) || removed
+                }
+            }
+        }
+        for (i in rowB.indices) {
+            val cellB = rowB[i]
+            if (cellB.mayBe(b, mayHaveSelection = false)) {
+                val cellAL = rowA.getOrNull(i - 1)
+                val cellAR = rowA.getOrNull(i + 1)
+                val cellCL = rowC.getOrNull(i - 1)
+                val cellCR = rowC.getOrNull(i + 1)
+
+                if (!(cellAL.mayBe(a) && cellCR.mayBe(c)) && !(cellCL.mayBe(c) && cellAR.mayBe(a))) {
+                    removed = cellB.options.remove(b) || removed
+                }
+            }
+        }
+
+        for (i in rowC.indices) {
+            val cellC = rowC[i]
+            if (cellC.mayBe(c, mayHaveSelection = false)) {
+                val cellBR = rowB.getOrNull(i + 1)
+                val cellAR = rowA.getOrNull(i + 2)
+                val cellBL = rowB.getOrNull(i - 1)
+                val cellAL = rowA.getOrNull(i - 2)
+
+                if (!(cellBR.mayBe(b) && cellAR.mayBe(a)) && !(cellBL.mayBe(b) && cellAL.mayBe(a))) {
+                    removed = cellC.options.remove(c) || removed
+                }
+            }
+        }
+
+        return removed
     }
 
     override fun toString(): String =