diff --git a/README.md b/README.md
index a733b3b..4dad047 100644
--- a/README.md
+++ b/README.md
@@ -27,7 +27,7 @@ In the end you should be able to run `pip3 --version` and `python3 -c "import sq
 
 Install additional python packages locally on the user area:
 
-    pip install --user tornado sqlalchemy pyyaml pygments markdown bcrypt
+    pip install --user tornado sqlalchemy pyyaml pygments markdown bcrypt networkx
 
 These are usually installed under
 
diff --git a/app.py b/app.py
index 698875a..bfaff8d 100644
--- a/app.py
+++ b/app.py
@@ -8,6 +8,8 @@ try:
     import bcrypt
     from sqlalchemy import create_engine
     from sqlalchemy.orm import sessionmaker
+    import networkx as nx
+    import yaml
 except ImportError:
     logger.critical('Python package missing. See README.md for instructions.')
     sys.exit(1)
@@ -24,10 +26,17 @@ logger = logging.getLogger(__name__)
 # ============================================================================
 class LearnApp(object):
     def __init__(self):
+        # online students
         self.online = {}
 
         # connect to database and check registered students
-        db = 'students.db'  # FIXME
+        self.setup_db('students.db')    # FIXME
+
+        # build dependency graph
+        self.build_dependency_graph({'uevora/lei'})  # FIXME
+
+    # ------------------------------------------------------------------------
+    def setup_db(self, db):
         engine = create_engine(f'sqlite:///{db}', echo=False)
         self.Session = sessionmaker(bind=engine)
         try:
@@ -59,7 +68,6 @@ class LearnApp(object):
                 'number': student.id,
                 'knowledge': Knowledge(),  # FIXME initial state?
             }
-            # print(self.online)
             return True
 
     # ------------------------------------------------------------------------
@@ -103,3 +111,37 @@ class LearnApp(object):
             raise
         finally:
             session.close()
+
+    # ------------------------------------------------------------------------
+    # Receives a set of topics (strings like "math/algebra"),
+    # and recursively adds dependencies to the dependency graph
+    def build_dependency_graph(self, topics=set()):
+        g = nx.DiGraph()
+
+        # add nodes "recursively" following the config.yaml files
+        while topics:
+            t = topics.pop()   # take one topic
+            if t in g.nodes(): # skip it if already in the graph
+                continue
+
+            # get configuration dictionary for this topic
+            # dictionary has keys: type, title, depends
+            try:
+                with open(f'topics/{t}/config.yaml', 'r') as f:
+                    logger.info(f'Loading {t}')
+                    config = yaml.load(f)
+            except FileNotFoundError:
+                logger.error(f'Not found: topics/{t}/config.yaml')
+                continue
+
+            config.setdefault('depends', set())  # make sure 'depends' key exists
+            topics.update(config['depends'])
+            g.add_node(t, config=config)
+
+        # add edges  topic -> dependency
+        for t in g.nodes():
+            deps = g.node[t]['config']['depends']
+            g.add_edges_from([(t, d) for d in deps])
+
+        self.depgraph = g
+        logger.info(f'Graph has {g.number_of_nodes()} nodes and {g.number_of_edges()} edges')
diff --git a/config/logger.yaml b/config/logger.yaml
index cb24382..445082a 100644
--- a/config/logger.yaml
+++ b/config/logger.yaml
@@ -5,7 +5,7 @@ formatters:
     void:
         format: ''
     standard:
-        format: '%(asctime)s | %(levelname)-8s | %(name)-14s | %(message)s'
+        format: '%(asctime)s | %(levelname)-8s | %(name)-8s | %(message)s'
 
 handlers:
     default:
diff --git a/serve.py b/serve.py
index f8d691b..caf1bcd 100755
--- a/serve.py
+++ b/serve.py
@@ -82,7 +82,6 @@ class LoginHandler(BaseHandler):
     def post(self):
         uid = self.get_body_argument('uid')
         pw = self.get_body_argument('pw')
-        # print(f'login.post:  user={uid},  pw={pw}')
 
         if self.learn.login(uid, pw):
             logging.info(f'User "{uid}" login ok.')
--
libgit2 0.21.2