Abstract: A method and apparatus of recognizing a pattern comprising a sequence of sub-patterns includes a set of possible patterns being modelled by a network of sub-pattern models. One or more initial software model objects are instantiated first. As these models produce outputs, succeeding model objects are instantiated if they have not already been instantiated. However, the succeeding model objects are only instantiated if a triggering model output meets a predetermined criterion. This ensures that the processing required is maintained at a manageable level. If the models comprise finite state networks, pruning of internal states may also be performed. The criterion applied to this pruning is less harsh than that applied when determining whether to instantiate a succeeding model.