Partial matching

[asmaloney]

Partial matching seems to have two distinct settings: "procedural partial matching" and "mismatch_penalty".

From the ACT-R manual:

:ppm
The procedural partial matching parameter controls whether productions are allowed to be selected and fired even if they are not a perfect match to the buffers’ current contents. If this parameter is set to a number then production matching is allowed to occur for buffer tests which are not a perfect match to the chunk in the buffer. The default value is nil which means productions will only match when the buffer tests are exact matches.

If the procedural partial matching is enabled, then slots tested for equality (slots without a modifier and those with an explicit = modifier) in buffer tests of productions may be considered a match even if the value is not chunk-slot-equal to the current value in the slot of the chunk in the buffer. The partial match will occur if there is a similarity value between the value specified for the slot in the production and the value currently in that slot of the buffer, as returned from the declarative module’s similarity command, and that similarity is greater than the maximum similarity difference.

:mp
The mismatch penalty parameter controls whether the partial matching system is enabled, and if so, specifies the value of the penalty parameter, P, in the activation equation. It can be set to any number or the value nil. The value nil means do not use partial matching (only exact matches can be retrieved), and is the default. If it is set to a number then partial matching is enabled.

It is unclear to me how these are supposed to be used.

• One Lisp example turns on :mp but not :ppm.
• Another Lisp example turns on :ppm but not :mp.
• Yet another turns them both on.
• The pyactr code seems to only use partial_matching in the declarative memory module to turn on the mismatch_penalty.
• ccm just has the Partial class which lets us set strength and limit.

So in vanilla they seem independent of each other and in pyactr, dependent.

Not sure what the intent is here since I don't fully understand the ACT-R descriptions. Can anyone add any clarity?