FRAMES (and FRL)

Frames - an AI programming technique

• A Representation structure
  • Frames
  • Slots
  • Facets
• Inheritance - information can come from the current frames or from frames higher up in the hierarchy
• Combined Code and Data - facet values can be triggers (code). Triggers can be executed based on changes of values or testing for a value.

The FRL language

• Frame - largest named structure
• Slot - name items within a frame
• Facet - lowest level of structure
  two basic types
  • $value - actual value
  • trigger - code to be executed under special conditions

Basic FRL Commands

• (fput <frame> <slot> '$value <value>)
  e.g.
  (fput 'tree 'use '$value 'fuel)
• (fget <frame> <slot> '$value)
  e.g.
  (fget 'tree 'use '$value)

• (fassert tree
    (use ($value (fuel)))
    (size ($value (large)))
  )
  

• (finstantiate 'tree)
• (fneed 'tree 'use)

Triggers

• $if-needed - invoked when fneed called for frame and slot
• $if-added - invoked after item added to slot
• $if-deleted - invoded after item deleted from slot

(fassert someframe
  (use ($if-needed ((ask_for frame- slot-))))
)

(defun ask_for (f s)
  (print `(enter value for ,f ,s)) (terpri)
  (fput f s '$value (read))
)

(fneed 'someframe 'use)
==>(enter value for someframe use)
==>next

(frame 'someframe)




The original papers on FRL are:

The FRL Primer
 AIM-408


and

The FRL Manual

AIM-409.