parse negation.

diff --git a/src/prolog/parser b/src/prolog/parser
index 5d8398b4e68def750e23d422b9b762c07a333ea8..29423d92d8793cbc82f686df4ac24cd9a0dd11d6 160000 (submodule)
--- a/src/prolog/parser
+++ b/src/prolog/parser
@@ -1 +1 @@
-Subproject commit 5d8398b4e68def750e23d422b9b762c07a333ea8
+Subproject commit 29423d92d8793cbc82f686df4ac24cd9a0dd11d6