1. A method for communicating accumulated state information between tasks in a learning system, comprising: encoding initial state representation for a hypothetical learning task indicating that no training instances have been received; receiving a training instance; if the training instance received reflects a new learning task, initializing a new learning task state representation based on the hypothetical learning task state representation; updating each learning task state representation except the hypothetical learning task using a target value stored for that task in the training instance; and updating the state representation for the hypothetical learning task using a default target value for the training instance.