From 2a297a74ca828db0c929ef3463c018e6f88bfb3c Mon Sep 17 00:00:00 2001
From: Florian Stecker <mail@florianstecker.de>
Date: Mon, 14 Nov 2016 11:54:52 +0100
Subject: [PATCH] find fixpoints in simplified graph

---
 generate.c | 30 ++++++++++++++++++++++--------
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/generate.c b/generate.c
index 818ac16..649f659 100644
--- a/generate.c
+++ b/generate.c
@@ -10,6 +10,7 @@ int main(int argc, const char *argv[])
   semisimple_type_t type;
   unsigned long right_invariance, left_invariance;
   int rank, order, hyperplanes, cosets;
+  int fixpoints;
 
   node_t *graph;
 
@@ -74,17 +75,30 @@ int main(int argc, const char *argv[])
   }
   fprintf(stderr, "\n\n");
 
-  // enumerate balanced thickenings
+  fixpoints = 0;
+  for(int i = 0; i < cosets; i++)
+    if(graph[i].opposite == i) {
+      if(fixpoints == 0)
+	fprintf(stderr, "No thickenings since the longest element fixes the following cosets: %s", alphabetize(graph[i].word, graph[i].wordlength, alphabet, string_buffer1));
+      else
+	fprintf(stderr, " %s", alphabetize(graph[i].word, graph[i].wordlength, alphabet, string_buffer1));
+      fixpoints++;
+    }
 
-  fwrite(&type.n, sizeof(int), 1, stdout);
-  fwrite(type.factors, sizeof(simple_type_t), type.n, stdout);
-  fwrite(&left_invariance, sizeof(unsigned long), type.n, stdout);
-  fwrite(&right_invariance, sizeof(unsigned long), type.n, stdout);
+  if(fixpoints > 0) {
+    fprintf(stderr, "\n\n");
+  } else {
 
-  long count = enumerate_balanced_thickenings(type, graph, cosets, alphabet, stdout);
+    // enumerate balanced thickenings
+    fwrite(&type.n, sizeof(int), 1, stdout);
+    fwrite(type.factors, sizeof(simple_type_t), type.n, stdout);
+    fwrite(&left_invariance, sizeof(unsigned long), type.n, stdout);
+    fwrite(&right_invariance, sizeof(unsigned long), type.n, stdout);
 
-  fprintf(stderr, "\n");
-  fprintf(stderr, "Found %ld balanced thickenings\n\n", count);
+    long count = enumerate_balanced_thickenings(type, graph, cosets, alphabet, stdout);
+
+    fprintf(stderr, "Found %ld balanced thickenings\n\n", count);
+  }
 
   graph_free(type, graph);
   free(type.factors);