Index: binaries/data/mods/public/simulation/ai/petra/researchManager.js
===================================================================
--- binaries/data/mods/public/simulation/ai/petra/researchManager.js
+++ binaries/data/mods/public/simulation/ai/petra/researchManager.js
@@ -35,43 +35,43 @@
 	}
 };
 
-PETRA.ResearchManager.prototype.researchPopulationBonus = function(gameState, queues)
+/**
+ * @param {string} modif - The path we try to improve.
+ * @param {string} affects - Optionally the class of entities we want to affect.
+ */
+PETRA.ResearchManager.prototype.tryImprove = function(gameState, queues, modif, affects)
 {
 	if (queues.minorTech.hasQueuedUnits())
-		return;
+		return false;
 
 	let techs = gameState.findAvailableTech();
 	for (let tech of techs)
 	{
-		if (!tech[1]._template.modifications)
-			continue;
-		// TODO may-be loop on all modifs and check if the effect if positive ?
-		if (tech[1]._template.modifications[0].value !== "Population/Bonus")
+		let template = tech[1]._template;
+		if (!template.modifications || affects && (!template.affects || template.affects.indexOf(affects) === -1))
 			continue;
-		queues.minorTech.addPlan(new PETRA.ResearchPlan(gameState, tech[0]));
-		break;
+		for (let i in template.modifications)
+		{
+			if (template.modifications[i].value === modif)
+			{
+				// ToDo: May-be check if the total effect is positive?
+				queues.minorTech.addPlan(new PETRA.ResearchPlan(gameState, tech[0]));
+				return true;
+			}
+		}
 	}
+	return false;
 };
 
-PETRA.ResearchManager.prototype.researchTradeBonus = function(gameState, queues)
+PETRA.ResearchManager.prototype.researchPopulationBonus = function(gameState, queues)
 {
-	if (queues.minorTech.hasQueuedUnits())
-		return;
+	this.tryImprove(gameState, queues, "Population/Bonus");
+};
 
-	let techs = gameState.findAvailableTech();
-	for (let tech of techs)
-	{
-		if (!tech[1]._template.modifications || !tech[1]._template.affects)
-			continue;
-		if (tech[1]._template.affects.indexOf("Trader") === -1)
-			continue;
-		// TODO may-be loop on all modifs and check if the effect if positive ?
-		if (tech[1]._template.modifications[0].value !== "UnitMotion/WalkSpeed" &&
-                    tech[1]._template.modifications[0].value !== "Trader/GainMultiplier")
-			continue;
-		queues.minorTech.addPlan(new PETRA.ResearchPlan(gameState, tech[0]));
-		break;
-	}
+PETRA.ResearchManager.prototype.researchTradeBonus = function(gameState, queues)
+{
+	this.tryImprove(gameState, queues, "UnitMotion/WalkSpeed", "Trader") ||
+		this.tryImprove(gameState, queues, "Trader/GainMultiplier", "Trader");
 };
 
 /** Techs to be searched for as soon as they are available */