X-Git-Url: http://nitlanguage.org

diff --git a/src/compiler/coloring.nit b/src/compiler/coloring.nit
index bff3243..80f29ec 100644
--- a/src/compiler/coloring.nit
+++ b/src/compiler/coloring.nit
@@ -160,9 +160,16 @@ end
 #
 # Possible colors:
 #
-# * A:0, B:1, C: 2, D: 1, E: 3, F:3, G:2, H:4
+# * A: 0
+# * B: 1
+# * C: 2
+# * D: 1
+# * E: 3
+# * F: 3
+# * G: 2
+# * H: 4
 #
-# see: Ducournau, R. (2011).
+# SEE: Ducournau, R. (2011).
 # Coloring, a versatile technique for implementing object-oriented languages.
 # Software: Practice and Experience, 41(6), 627–659.
 class POSetColorer[E: Object]
@@ -171,6 +178,9 @@ class POSetColorer[E: Object]
 	var is_colored = false
 
 	# Resulting ids
+	#
+	# All ids are strictly positive (`>= 1`).
+	#
 	# REQUIRE: is_colored
 	fun ids: Map[E, Int] do
 		assert is_colored
@@ -216,7 +226,7 @@ class POSetColorer[E: Object]
 		ids_cache.clear
 		var elements = new HashSet[E].from(poset_cache.to_a)
 		for e in poset_cache.linearize(elements) do
-			ids_cache[e] = ids_cache.length
+			ids_cache[e] = ids_cache.length + 1
 		end
 	end