diff --git a/source/engine/generateQuestions.js b/source/engine/generateQuestions.js
index 1e43c77ef..42a653926 100644
--- a/source/engine/generateQuestions.js
+++ b/source/engine/generateQuestions.js
@@ -126,6 +126,15 @@ export let buildNextSteps = (allRules, analysedSituation) => {
 		D'autres variables pourront être regroupées aussi, car elles partagent un parent, mais sans fusionner leurs questions dans l'interface. Ce sont des **groupes de type _record_ **
 	*/
 
+	// This is effectively a missingVariables.groupBy(questionRequired)
+	// but "questionRequired" does not have a clear specification
+	// we could look up "what formula is this variable mentioned in, and does it have a question attached"
+	// the problem is that we parse rules "bottom up", we would therefore need to:
+	// - parse rules top-down, i.e. analysedSituations = map(treatRuleRoot, rules)
+	// (might be a problem later on in terms of "big" rulesets, but not now)
+	// - decorate each rule with "mentions / depends on the following rules"
+	// - provide a "is mentioned by" query
+
 	return R.pipe(
 		R.keys,
 		R.curry(findVariantsAndRecords)(allRules),
diff --git a/source/reducers.js b/source/reducers.js
index b37e79986..58d9e3ca7 100644
--- a/source/reducers.js
+++ b/source/reducers.js
@@ -5,10 +5,20 @@ import reduceReducers from 'reduce-reducers'
 import {reducer as formReducer, formValueSelector} from 'redux-form'
 
 import {rules} from 'Engine/rules'
-import {analyse, buildNextSteps, generateGridQuestions, generateSimpleQuestions} from 'Engine/generateQuestions'
+import {buildNextSteps, generateGridQuestions, generateSimpleQuestions} from 'Engine/generateQuestions'
 import computeThemeColours from 'Components/themeColours'
-import { EXPLAIN_VARIABLE, POINT_OUT_OBJECTIVES} from './actions'
-import { STEP_ACTION, START_CONVERSATION} from './actions'
+import { STEP_ACTION, START_CONVERSATION, EXPLAIN_VARIABLE, POINT_OUT_OBJECTIVES, CHANGE_THEME_COLOUR} from './actions'
+
+import {analyseSituation} from 'Engine/traverse'
+
+let situationGate = state =>
+	name => formValueSelector('conversation')(state, name)
+
+let analyse = rootVariable => R.pipe(
+	situationGate,
+	// une liste des objectifs de la simulation (des 'rules' aussi nommées 'variables')
+	analyseSituation(rules, rootVariable)
+)
 
 export let reduceSteps = (state, action) => {
 
@@ -51,7 +61,7 @@ export let reduceSteps = (state, action) => {
 }
 
 function themeColours(state = computeThemeColours(), {type, colour}) {
-	if (type == 'CHANGE_THEME_COLOUR')
+	if (type == CHANGE_THEME_COLOUR)
 		return computeThemeColours(colour)
 	else return state
 }