Looking for a reasoner demo

Dear all,

Next semester I'm going to teach "Knowledge-based systems". As a bait I
would like to use a short demo (video or downloadable) of such a system
implemented in Prolog. I'm particularly interested in (non-monotonic,
fuzzy, etc.) reasoners. The demo should be nice, colorful and flashy,
and should not assume specific domain knowledge of the audience.

Best regards,
Alexander

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