Following is a demo of the Picnic Belief Revision program.
This scenario models belief revision when the forecast is favorable for a picnic, and the conditions remain favorable.
?- picnic. Walking outside, the current weather looks good for a picnic later... It is currently sunny with mild temperatures, no humidity, and calm winds The current forecast looks good for a picnic later... The forecast has a temperature of 73° with sunny conditions, 48° dewpoints, and 4 MPH winds with a 22% chance of precipitation. It is now time for the picnic... Walking outside, the weather still looks good for a picnic... It is currently sunny with mild temperatures, no humidity, and calm winds The weather turned out to be great for the picnic, so you decide to go and have one! true