From d604e44dffdfe2ab021bec7e5579eb36514213a3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Patrick=20L=C3=BChne?= <patrick-github@luehne.de>
Date: Sun, 14 Aug 2016 16:00:31 +0200
Subject: [PATCH] Documented mutex groups.

---
 doc/output-format.md | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/doc/output-format.md b/doc/output-format.md
index 6cb804a..e81d46f 100644
--- a/doc/output-format.md
+++ b/doc/output-format.md
@@ -161,3 +161,19 @@ goal(<variable>, <value>).
 ```
 
 The goal specifies all variable assignments that have to be fulfilled after executing the plan.
+
+### Mutex Groups
+
+```prolog
+% declares a <mutex group>
+mutexGroup(mutexGroup(<number>)).
+
+% adds the assignment of <variable> to <value> to a <mutex group>
+contains(<mutex group>, <variable>, <value>).
+```
+
+SAS contains information about mutually exclusive variable assignments.
+That is, *at most one* variable assignment of each mutex group must be satisfied at all times.
+
+Mutex groups contain essential information in order to find plans correctly.
+That is, if mutex groups are present in `plasp`’s output, they have to be accounted for appropriately.