Implementing persistence of derived information in a reason maintenance system

Class of deductions where their conclusions persist even though some components of justification are no more valid, pose some difficulty in reasoning about change. A partial solution is found in the notion called inessentiality of a component of a justification to its conclusion. The frame axiom to deduce the persistence of a sentence using the notion of inessentiality is accommodated within the framework of Reason Maintenance System (RMS), by modifying the definition of IN-ness of a node and its current-support.