Oct 20
aside
Two things to do:
- finish midterm search projects (so I'm not assigning other written work now)
- read / explore material on knowledge representation ... which we'll discuss today.
chap 10 : agents & First Order Logic
logic for agent actions :
- Result(situation, action) is another situation
- Poss(action, situation) is true if that action can be performed in that situation.
- fluent : world state variable; value can change over time (i.e. is fluid)
chap 12 : ontology
Ontologies are similar in intent to relational databases
(this is a member of that class related to these and those)
but are intended to be more general, including logically implying
new relations between many "databases".
Discuss basics of relational databases.
Here's an article discussing object oriented programming vs ontologies
Note "closed world" vs "open world" assumptions about
facts not explicitly stated as true and the sorts of reasoning that follows.
projects / software systems
opencyc.org :
dbpedia :
protege knowledge browser :
OWL and the semantic web
- The WWW version has gone through several revisions;
- now known as OWL (Web Ontology Language) - yes I know the order is wrong; see
- http://www.w3.org/TR/owl-guide/ and the OWL2 2009 update*
- http://www.w3.org/TR/owl2-overview/
- Note several syntax frameworks here : XML > RDF > OWL
- lots of acronyms, lots of work, ... still hasn't really caught on
- "Turtle" is its simplified language of triples (subject verb object)
SPARQL :
openmind.org
- another collaborative project to build a big ontology
example ontologies
creative commons licenses
Example in HTML webpage :
<a rel="license" href="http://creativecommons.org/licenses/by-nc-sa/3.0/">
<img alt="Creative Commons License" style="border-width:0"
src="http://i.creativecommons.org/l/by-nc-sa/3.0/80x15.png" />
</a><br />
<span xmlns:dct="http://purl.org/dc/terms/" property="dct:title">an example</span> by
<span xmlns:cc="http://creativecommons.org/ns#" property="cc:attributionName">Jim Mahoney</span>
is licensed under a
<a rel="license" href="http://creativecommons.org/licenses/by-nc-sa/3.0/">
Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License
</a>.
... which uses RDFa ;
see also
The basic idea is that RDF encodes "triples": subject predicate object,
e.g. "this_webpage author 'Jim Mahoney'".
In the CC example above, the subject of the declarations is implied
to be the current webpage. xmlns is "XML Name Space" and give an abbreviation
for a URL as a global "name" of a concept. i.e. "title".
RSS
"really simple syndication" or "RDF Site Summary"
FOAF
www.foaf-project.org
internet shopping world
browse material in section 12.7 in the text
Look at 1st problem in text, chapter 12, and textbook's solution
