Young and O'Shea's model of Arithmetic

Production rule model of multi-column subtraction: contains a fairly small number of simple production rules.models children's errors by deleting rules from a model that works correctly.accounts for a large percentage of errors found in practice.supports hypothesis that many errors arise from forgetting a sub-skill. Young and O'Shea stress that rules do not form a structurally delimited module: If during subtraction, circumstances are appropriate for triggering other rules, they will fire.

The Young and O'Shea (1981) model provides a good illustration of many of the strengths of production systems and production system modelling. The production system interpreter provides a domain general system for executing or enacting the production rules, each of which specifies a unit of task knowledge. The knowledge units are self-contained in the sense that they may be added or deleted to yield different behaviours. This clarifies how algorithm errors may arise. It also clarifies how rules from n

Description

Implementation

Faulty rules

Discussion