diff --git a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/model/Pairable.kt b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/model/Pairable.kt
index bee62a4..43356e2 100644
--- a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/model/Pairable.kt
+++ b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/model/Pairable.kt
@@ -9,7 +9,7 @@ import org.jeudego.pairgoth.store.Store
 sealed class Pairable(val id: ID, val name: String, open val rating: Int, open val rank: Int) {
     companion object {
         val MIN_RANK: Int = -30 // 30k
-        val MAX_RANK: Int = 20
+        val MAX_RANK: Int = 8 // 9D
     }
     abstract fun toJson(): Json.Object
     abstract val club: String?
diff --git a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/model/Pairing.kt b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/model/Pairing.kt
index 08e5208..4de0168 100644
--- a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/model/Pairing.kt
+++ b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/model/Pairing.kt
@@ -181,8 +181,8 @@ class MacMahon(
     placementParams: PlacementParams = PlacementParams(
         Criterion.NBW, Criterion.SOSW, Criterion.SOSOSW
     ),
-    var mmFloor: Int = -20,
-    var mmBar: Int = 0
+    var mmFloor: Int = -20, // 20k
+    var mmBar: Int = 0 // 1D
 ): Pairing(MAC_MAHON, pairingParams, placementParams) {
     companion object {}
     override fun pair(tournament: Tournament<*>, round: Int, pairables: List<Pairable>): List<Game> {
diff --git a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/solver/BaseSolver.kt b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/solver/BaseSolver.kt
index 6fa67d6..b0053d5 100644
--- a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/solver/BaseSolver.kt
+++ b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/solver/BaseSolver.kt
@@ -236,8 +236,7 @@ sealed class BaseSolver(
     open fun MainCritParams.minimizeScoreDifference(p1: Pairable, p2: Pairable): Double {
         var score = 0.0
         val scoreRange: Int = groupsCount
-        // TODO check category equality if category are used in SwissCat
-        if (scoreRange!=0){
+        if (scoreRange != 0){
             val x = abs(p1.group - p2.group).toDouble() / scoreRange.toDouble()
             score = concavityFunction(x, scoreWeight)
         }
diff --git a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/solver/MacMahonSolver.kt b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/solver/MacMahonSolver.kt
index aab764b..4061ff4 100644
--- a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/solver/MacMahonSolver.kt
+++ b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/solver/MacMahonSolver.kt
@@ -13,17 +13,18 @@ class MacMahonSolver(round: Int,
     BaseSolver(round, history, pairables, pairingParams, placementParams) {
 
     override val scores: Map<ID, Double> by lazy {
-        historyHelper.wins.mapValues {
-            pairablesMap[it.key]!!.let { pairable ->
-                pairable.mmBase + pairable.nbW
-            }
-        }
+        pairablesMap.mapValues { it.value.let {
+            pairable -> pairable.mmBase + pairable.nbW // TODO take tournament parameter into account
+        } }
     }
+
     val Pairable.mmBase: Double get() = min(max(rank, mmFloor), mmBar) + mmsZero
     val Pairable.mms: Double get() = scores[id] ?: 0.0
 
     // CB TODO - configurable criteria
-    override val mainLimits get() = Pair(mmFloor.toDouble(), 100.0) // TODO ?
+    val mainScoreMin = mmFloor + PLA_SMMS_SCORE_MIN - Pairable.MIN_RANK
+    val mainScoreMax = mmBar + PLA_SMMS_SCORE_MAX + (round-1) - Pairable.MIN_RANK // round number starts at 1
+    override val mainLimits get() = Pair(mainScoreMin.toDouble(), mainScoreMax.toDouble())
     override fun evalCriterion(pairable: Pairable, criterion: Criterion) = when (criterion) {
         Criterion.MMS -> pairable.mms
         Criterion.SOSM -> pairable.sos
@@ -35,6 +36,8 @@ class MacMahonSolver(round: Int,
 
     companion object {
         const val mmsZero = 30.0
+        const val PLA_SMMS_SCORE_MAX = 2 // TODO move this into placement criteria
+        const val PLA_SMMS_SCORE_MIN = -1
     }
 
 }