diff --git a/knowledge/README.txt b/knowledge/README.txt
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+++ b/knowledge/README.txt
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+Knowledge management, learning, and similar stuff
+=================================================
+
+  ($Id$)
+
+Let's first set up a tree of knowledge elements (topics) and their
+interdependencies:
+
+  >>> from cybertools.knowledge.element import KnowledgeElement
+  >>> progLang = KnowledgeElement()
+  >>> ooProg = KnowledgeElement()
+  >>> python = KnowledgeElement()
+  >>> pyBasics = KnowledgeElement()
+  >>> pyOo = KnowledgeElement()
+  >>> pySpecials = KnowledgeElement()
+
+The knowledge may be organized in a hierarchy (taxonomy) of topics; we
+don't use this at the moment but it is important to give the knowledge
+an overall structure.
+
+  >>> python.parent = progLang
+  >>> pyBasics.parent = python
+  >>> pyOo.parent = python
+  >>> pySpecials.parent = python
+
+An important point here is that a knowledge element may depend on another;
+this means that somebody first has to acquire one of the knowledge elements
+before being able to acquire a dependent element. In our example one
+would first have to study object-oriented programming in general and the
+Python basics before being able to study object oriented programming
+with Python.
+
+  >>> pyOo.dependsOn(ooProg)
+  >>> pyOo.dependsOn(pyBasics)
+
+Now we create a person that knows about basic Python programming:
+
+  >>> from cybertools.knowledge.knowing import Knowing
+  >>> john = Knowing()
+  >>> john.knows(pyBasics)
+
+Next we have a position that requires knowledge in object-oriented
+programming with Python:
+
+  >>> from cybertools.knowledge.position import Position
+  >>> pos01 = Position()
+  >>> pos01.requires(pyOo)
+
+Now we can ask what knowledge john is lacking if he would like to take
+the position offered:
+
+  >>> john.getMissingKnowledge(pos01) == (ooProg, pyOo,)
+  True  
+
+Luckily there are a few elearning content objects out there that
+provide some of the knowledge needed:
+
+  >>> from cybertools.knowledge.provider import KnowledgeProvider
+  >>> doc01 = KnowledgeProvider()
+  >>> doc02 = KnowledgeProvider()
+
+  >>> doc01.provides(ooProg)
+  >>> doc02.provides(pyOo)
+
+So that we are now able to find out what john has to study in order to
+fulfill the position offered:
+
+  >>> list(john.getProvidersNeeded(pos01))
+  
+
diff --git a/knowledge/__init__.py b/knowledge/__init__.py
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+++ b/knowledge/__init__.py
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+"""
+$Id$
+"""
+
diff --git a/knowledge/element.py b/knowledge/element.py
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--- /dev/null
+++ b/knowledge/element.py
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+#
+#  Copyright (c) 2006 Helmut Merz helmutm@cy55.de
+#
+#  This program is free software; you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation; either version 2 of the License, or
+#  (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software
+#  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+#
+
+"""
+Represent knowledge elements and their interrelations.
+
+$Id$
+"""
+
+from zope.interface import implements
+from cybertools.knowledge.interfaces import IKnowledgeElement
+
+
+class KnowledgeElement(object):
+
+    implements(IKnowledgeElement)
+    
+    def __init__(self):
+        self._parent = None
+        self._dependencies = {}
+        # backlinks:
+        self._children = set()
+        self._dependents = set()
+        self._knowers = set()
+        self._requiringPositions = set()
+        self._providers = set()
+
+    def setParent(self, obj):
+        old = self._parent
+        if old is not None and old != obj:
+            del old._children[self]
+        if obj is not None and old != obj:
+            obj._children.add(self)
+        self._parent = obj
+    def getParent(self): return self._parent
+    parent = property(getParent, setParent)
+
+    def getDependencies(self):
+        return self._dependencies
+
+    def dependsOn(self, obj):
+        self._dependencies[obj] = True
+        obj._dependents.add(self)
+
+    def removeDependency(self, obj):
+        del self._dependencies[obj]
+        del obj._dependents[self]
+
+    def getDependents(self):
+        return self._dependents
+
+    def getKnowers(self):
+        return self._knowers
+
+    def getProviders(self):
+        return tuple(self._providers)
+
diff --git a/knowledge/interfaces.py b/knowledge/interfaces.py
new file mode 100644
index 0000000..531ab4b
--- /dev/null
+++ b/knowledge/interfaces.py
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+#
+#  Copyright (c) 2006 Helmut Merz helmutm@cy55.de
+#
+#  This program is free software; you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation; either version 2 of the License, or
+#  (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software
+#  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+#
+
+"""
+Interfaces for knowledge management and e-learning.
+
+$Id$
+"""
+
+from zope.interface import Interface, Attribute
+from zope import schema
+from zope.i18nmessageid import MessageFactory
+
+_ = MessageFactory('zope')
+
+
+class IKnowledgeElement(Interface):
+    """ An entity denoting some sort of knowledge.
+    """
+
+    parent = Attribute('An optional parent element (sort of parent topic)')
+
+    def getDependencies():
+        """ Return a collection of knowledge elements this object depends on.
+        """
+
+    def dependsOn(element):
+        """ Add an element to the collection of elements this object
+            depends on.
+        """
+
+    def removeDependency(element):
+        """ Remove the element given from the collection of elements
+            this object depends on.
+        """
+
+    def getDependents():
+        """ Return a collection of knowledge elements that are depending
+            on this object.
+        """
+
+    def getKnowers():
+        """ Return a collection of Knowing objects that have this object
+            in their knowledge portfolio.
+        """
+
+    def getProviders():
+        """ Return a collection of knowledge providers that provide this
+            object. 
+        """
+
+
+class IKnowing(Interface):
+    """ Someone who knows something.
+    """
+
+    def getKnowledge():
+        """ Return the collection of elements that constitute the
+            knowledge of this object.
+        """
+
+    def knows(self, element):
+        """ Add an element to the collection of elementsthat constitute the
+            knowledge of this object.
+        """
+
+    def removeKnowledge(element):
+        """ Remove the element given from the collection of elements
+            that constitute the knowledge of this object.
+        """
+
+    def getMissingKnowledge(position):
+        """ Return a tuple of knowledge elements that this object
+            is missing for fulfilling the position given.
+        """
+
+    def getProvidersNeeded(position):
+        """ Return two tuples: first a tuple of knowledge providers that
+            provide knowledge needed for fulfilling the position given,
+            second a tuple with the requirements that could not
+            be met by the available knowledge providers.
+        """
+
+
+class IPosition(Interface):
+    """ A position requires a certain knowledge.
+    """
+
+    def getRequirements():
+        """ Return the collection of knowledge elements this object requires.
+        """
+
+    def requires(element):
+        """ Add a knowledge element to the collection of elements this
+            object requires.
+        """
+
+    def removeKnowledge(element):
+        """ Remove the element given from the collection of elements
+            this object requires.
+        """
+
+
+class IKnowledgeProvider(Interface):
+    """ An object that is able to provide a certain knowledge - that may
+        be a document or some sort of elearning content, ...
+    """
+
+    def getProvidedKnowledge():
+        """ Return a collection of knowledge elements this object provides.
+        """
+
+    def provides(element):
+        """ Add a knowledge element to the collection of elements this
+            object provides.
+        """
+
+    def removeProvidedKnowledge(element):
+        """ Remove the element given from the collection of elements
+            this object provides.
+        """
+
+
+
diff --git a/knowledge/knowing.py b/knowledge/knowing.py
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index 0000000..8ef0877
--- /dev/null
+++ b/knowledge/knowing.py
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+#
+#  Copyright (c) 2006 Helmut Merz helmutm@cy55.de
+#
+#  This program is free software; you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation; either version 2 of the License, or
+#  (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software
+#  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+#
+
+"""
+Manage objects (people) who know something.
+
+$Id$
+"""
+
+from zope.interface import implements
+from cybertools.knowledge.interfaces import IKnowing
+
+
+class Knowing(object):
+
+    implements(IKnowing)
+
+    def __init__(self):
+        self._knowledge = {}
+
+    def getKnowledge(self):
+        return self._knowledge
+
+    def knows(self, obj):
+        self._knowledge[obj] = True
+        obj._knowers.add(self)
+
+    def removeKnowledge(self, obj):
+        del self._knowledge[obj]
+        del obj._knowers[self]
+
+    def getMissingKnowledge(self, position):
+        # to be done
+        return tuple(position.getRequirements())
+
+    def getProvidersNeeded(self, position):
+        return ((k, k.getProviders())
+                    for k in self.getMissingKnowledge(position))
+
+
diff --git a/knowledge/position.py b/knowledge/position.py
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index 0000000..7f52ab1
--- /dev/null
+++ b/knowledge/position.py
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+#
+#  Copyright (c) 2006 Helmut Merz helmutm@cy55.de
+#
+#  This program is free software; you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation; either version 2 of the License, or
+#  (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software
+#  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+#
+
+"""
+Represent positions that require certain knowledge.
+
+$Id$
+"""
+
+from zope.interface import implements
+from cybertools.knowledge.interfaces import IPosition
+
+
+class Position(object):
+
+    implements(IPosition)
+    
+    def __init__(self):
+        self._requirements = {}
+
+    def getRequirements(self):
+        return self._requirements
+
+    def requires(self, obj):
+        self._requirements[obj] = True
+        obj._requiringPositions.add(self)
+
+    def removeRequirement(self, obj):
+        del self._requirements[obj]
+        del obj._requiringPositions[self]
+
diff --git a/knowledge/provider.py b/knowledge/provider.py
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index 0000000..73c608b
--- /dev/null
+++ b/knowledge/provider.py
@@ -0,0 +1,46 @@
+#
+#  Copyright (c) 2006 Helmut Merz helmutm@cy55.de
+#
+#  This program is free software; you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation; either version 2 of the License, or
+#  (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software
+#  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+#
+
+"""
+Knowledge providers provide knowledge.
+
+$Id$
+"""
+
+from zope.interface import implements
+from cybertools.knowledge.interfaces import IKnowledgeProvider
+
+
+class KnowledgeProvider(object):
+
+    implements(IKnowledgeProvider)
+    
+    def __init__(self):
+        self._providedKnowledge = {}
+
+    def getProvidedKnowledge(self):
+        return self._providedKnowledge
+
+    def provides(self, obj):
+        self._providedKnowledge[obj] = True
+        obj._providers.add(self)
+
+    def removeDependency(self, obj):
+        del self._providedKnowledge[obj]
+        del obj._providers[self]
+
diff --git a/knowledge/tests.py b/knowledge/tests.py
new file mode 100755
index 0000000..7391542
--- /dev/null
+++ b/knowledge/tests.py
@@ -0,0 +1,28 @@
+#! /usr/bin/python
+
+"""
+Tests for the 'cybertools.knowledge' package.
+
+$Id$
+"""
+
+import unittest, doctest
+from zope.testing.doctestunit import DocFileSuite
+from cybertools.knowledge.knowing import Knowing
+
+class TestKnowledge(unittest.TestCase):
+    "Basic tests for the knowledge package."
+
+    def testBasicStuff(self):
+        p = Knowing()
+
+
+def test_suite():
+    flags = doctest.NORMALIZE_WHITESPACE | doctest.ELLIPSIS
+    return unittest.TestSuite((
+        unittest.makeSuite(TestKnowledge),
+        DocFileSuite('README.txt', optionflags=flags),
+        ))
+
+if __name__ == '__main__':
+    unittest.main(defaultTest='test_suite')