diff --git a/api-webapp/pom.xml b/api-webapp/pom.xml
index 2afa95d..f16fb6f 100644
--- a/api-webapp/pom.xml
+++ b/api-webapp/pom.xml
@@ -158,7 +158,7 @@
         <dependency>
             <groupId>com.republicate.kson</groupId>
             <artifactId>essential-kson-jvm</artifactId>
-            <version>2.3</version>
+            <version>2.4</version>
         </dependency>
         <!-- charset detection
         <dependency>
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 335edab..ea999f6 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
@@ -14,13 +14,13 @@ data class BaseCritParams(
     val dupWeight: Double = MAX_AVOIDDUPGAME,
     val random: Double = 0.0,
     val deterministic: Boolean = true,
-    val colorBalance: Double = MAX_COLOR_BALANCE
+    val colorBalanceWeight: Double = MAX_COLOR_BALANCE
 ) {
     init {
         if (nx1 < 0.0 || nx1 > 1.0) throw Error("invalid standardNX1Factor")
         if (dupWeight < 0.0 || dupWeight > MAX_AVOIDDUPGAME) throw Error("invalid avoidDuplGame value")
         if (random < 0.0 || random > MAX_RANDOM) throw Error("invalid random")
-        if (colorBalance > 0.0 || colorBalance > MAX_COLOR_BALANCE) throw Error("invalid balanceWB")
+        if (colorBalanceWeight < 0.0 || colorBalanceWeight > MAX_COLOR_BALANCE) throw Error("invalid ColorBalanceWeight")
     }
 
     companion object {
@@ -189,14 +189,14 @@ fun BaseCritParams.Companion.fromJson(json: Json.Object) = BaseCritParams(
     dupWeight = json.getDouble("dupWeight") ?: default.dupWeight,
     random = json.getDouble("random") ?: default.random,
     deterministic = json.getBoolean("deterministic") ?: default.deterministic,
-    colorBalance = json.getDouble("colorBalanceWeight") ?: default.colorBalance
+    colorBalanceWeight = json.getDouble("colorBalanceWeight") ?: default.colorBalanceWeight
 )
 
 fun BaseCritParams.toJson() = Json.Object(
     "nx1" to nx1,
     "dupWeight" to dupWeight,
     "random" to random,
-    "colorBalanceWeight" to colorBalance
+    "colorBalanceWeight" to colorBalanceWeight
 )
 
 fun MainCritParams.Companion.fromJson(json: Json.Object) = MainCritParams(
diff --git a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/HistoryHelper.kt b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/HistoryHelper.kt
index 372cb0e..5c7c0b5 100644
--- a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/HistoryHelper.kt
+++ b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/HistoryHelper.kt
@@ -3,7 +3,7 @@ package org.jeudego.pairgoth.pairing
 import org.jeudego.pairgoth.model.*
 import org.jeudego.pairgoth.model.Game.Result.*
 
-open class HistoryHelper(protected val history: List<List<Game>>, private val scores: Map<ID, Double>) {
+open class HistoryHelper(protected val history: List<List<Game>>, scoresGetter: ()-> Map<ID, Double>) {
 
     private val Game.blackScore get() = when (result) {
         BLACK, BOTHWIN -> 1.0
@@ -15,6 +15,8 @@ open class HistoryHelper(protected val history: List<List<Game>>, private val sc
         else -> 0.0
     }
 
+    private val scores by lazy(scoresGetter)
+
     // Generic helper functions
     open fun playedTogether(p1: Pairable, p2: Pairable) = paired.contains(Pair(p1.id, p2.id))
     open fun colorBalance(p: Pairable) = colorBalance[p.id]
@@ -137,8 +139,8 @@ open class HistoryHelper(protected val history: List<List<Game>>, private val sc
 
 // CB TODO - a big problem with the current naive implementation is that the team score is -for now- the sum of team members individual scores
 
-class TeamOfIndividualsHistoryHelper(history: List<List<Game>>, scores: Map<ID, Double>):
-        HistoryHelper(history, scores) {
+class TeamOfIndividualsHistoryHelper(history: List<List<Game>>, scoresGetter: () -> Map<ID, Double>):
+        HistoryHelper(history, scoresGetter) {
 
     private fun Pairable.asTeam() = this as TeamTournament.Team
 
diff --git a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/MacMahonSolver.kt b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/MacMahonSolver.kt
index 962b79d..751b336 100644
--- a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/MacMahonSolver.kt
+++ b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/MacMahonSolver.kt
@@ -20,7 +20,7 @@ class MacMahonSolver(round: Int,
     val Pairable.mms: Double get() = scores[id] ?: 0.0
 
     // CB TODO - configurable criteria
-    override val mainLimits get() = TODO()
+    override val mainLimits get() = Pair(0.0, 100.0) // TODO
     override fun evalCriterion(pairable: Pairable, criterion: Criterion) = when (criterion) {
         Criterion.MMS -> pairable.mms
         else -> super.evalCriterion(pairable, criterion)
diff --git a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/Solver.kt b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/Solver.kt
index cf0b74d..b225491 100644
--- a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/Solver.kt
+++ b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/Solver.kt
@@ -48,10 +48,8 @@ sealed class Solver(
     }
 
     abstract val scores: Map<ID, Double>
-    val historyHelper by lazy {
-        if (pairables.first().let { it is TeamTournament.Team && it.teamOfIndividuals }) TeamOfIndividualsHistoryHelper(history, scores)
-        else HistoryHelper(history, scores)
-    }
+    val historyHelper = if (pairables.first().let { it is TeamTournament.Team && it.teamOfIndividuals }) TeamOfIndividualsHistoryHelper(history) { scores }
+        else HistoryHelper(history) { scores }
 
     // pairables sorted using overloadable sort function
     private val sortedPairables by lazy {
@@ -139,8 +137,8 @@ sealed class Solver(
         if (potentialHd == 0) {
             val wb1: Int = p1.colorBalance
             val wb2: Int = p2.colorBalance
-            if (wb1 * wb2 < 0) return colorBalance
-            else if (wb1 == 0 && abs(wb2) >= 2 || wb2 == 0 && abs(wb1) >= 2) return colorBalance / 2
+            if (wb1 * wb2 < 0) return colorBalanceWeight
+            else if (wb1 == 0 && abs(wb2) >= 2 || wb2 == 0 && abs(wb1) >= 2) return colorBalanceWeight / 2
         }
         return 0.0
     }
@@ -239,7 +237,7 @@ sealed class Solver(
 
         // Same country
         val countryRatio = if (p1.country != p2.country && countryFactor != 0) {
-            min(countryFactor.toDouble() / placementScoreRange as Double, 1.0) // clamp to 1
+            min(countryFactor.toDouble() / placementScoreRange.toDouble(), 1.0) // clamp to 1
         } else {
             0.0
         }
@@ -253,14 +251,14 @@ sealed class Solver(
             clubRatio = if (clubFactor == 0) {
                 0.0
             } else {
-                clubFactor.toDouble() / 2.0 / placementScoreRange as Double
+                clubFactor.toDouble() / 2.0 / placementScoreRange.toDouble()
             }
 
         } else if (!commonGroup && !commonClub) {
             clubRatio = if (clubFactor == 0) {
                 0.0
             } else {
-                clubFactor.toDouble() * 1.2 / placementScoreRange as Double
+                clubFactor.toDouble() * 1.2 / placementScoreRange.toDouble()
             }
         }
         clubRatio = min(clubRatio, 1.0)
diff --git a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/SwissSolver.kt b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/SwissSolver.kt
index 8b75346..d4dc7b7 100644
--- a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/SwissSolver.kt
+++ b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/SwissSolver.kt
@@ -1,6 +1,7 @@
 package org.jeudego.pairgoth.pairing
 
 import org.jeudego.pairgoth.model.*
+import kotlin.properties.Delegates
 
 class SwissSolver(round: Int,
                   history: List<List<Game>>,
@@ -11,8 +12,11 @@ class SwissSolver(round: Int,
 
     // In a Swiss tournament the main criterion is the number of wins and already computed
 
-    override val scores: Map<ID, Double>
-        get() = historyHelper.wins
+    override val scores by lazy {
+        historyHelper.wins
+    }
+    //
+    // get() by lazy { historyHelper.wins }
 
     override val mainLimits = Pair(0.0, round - 1.0)
 }
diff --git a/api-webapp/src/test/kotlin/BasicTests.kt b/api-webapp/src/test/kotlin/BasicTests.kt
index b408da5..c16aa35 100644
--- a/api-webapp/src/test/kotlin/BasicTests.kt
+++ b/api-webapp/src/test/kotlin/BasicTests.kt
@@ -1,6 +1,7 @@
 package org.jeudego.pairgoth.test
 
 import com.republicate.kson.Json
+import com.republicate.kson.toJsonObject
 import org.jeudego.pairgoth.model.ID
 import org.junit.jupiter.api.MethodOrderer.MethodName
 import org.junit.jupiter.api.Test
@@ -53,7 +54,7 @@ class BasicTests: TestBase() {
         ),
         "rounds" to 2,
         "pairing" to Json.Object(
-            "type" to "MACMAHON"
+            "type" to "MAC_MAHON"
         )
     )
 
@@ -94,8 +95,10 @@ class BasicTests: TestBase() {
         val resp = TestAPI.get("/api/tour/$aTournamentID").asObject()
         assertEquals(aTournamentID, resp.getInt("id"), "First tournament should have id #$aTournamentID")
         // filter out "id", and also "komi", "rules" and "gobanSize" which were provided by default
-        val cmp = Json.Object(*resp.entries.filter { it.key !in listOf("id", "komi", "rules", "gobanSize") }.map { Pair(it.key, it.value) }.toTypedArray())
-        assertEquals(aTournament.toString(), cmp.toString(), "tournament differs")
+        // also filter out "pairing", which is filled by all default values
+        val cmp = Json.Object(*resp.entries.filter { it.key !in listOf("id", "komi", "rules", "gobanSize", "pairing") }.map { Pair(it.key, it.value) }.toTypedArray())
+        val expected = aTournament.entries.filter { it.key != "pairing" }.map { Pair(it.key, it.value) }.toMap().toJsonObject()
+        assertEquals(expected.toString(), cmp.toString(), "tournament differs")
     }
 
     @Test
diff --git a/view-webapp/pom.xml b/view-webapp/pom.xml
index 9779fd1..95f6b77 100644
--- a/view-webapp/pom.xml
+++ b/view-webapp/pom.xml
@@ -216,7 +216,7 @@
         <dependency>
             <groupId>com.republicate.kson</groupId>
             <artifactId>essential-kson-jvm</artifactId>
-            <version>2.3</version>
+            <version>2.4</version>
         </dependency>
         <!-- charset detection
         <dependency>