Finally, a schema for a certain mathematical concept is an individual’s collection of actions, processes, objects, and other schemas which are linked by some general principles to form a framework in the individual’s mind that may be brought to bear upon a problem situation involving that concept. This framework must be coherent in the sense that it gives, explicitly or implicitly, means of determining which phenomena are in the scope of the schema and which are not. Because this theory considers that all mathematical entities can be represented in terms of actions, processes, objects, and schemas, the idea of schema is very similar to the concept image which Tall and Vinner introduce in“ Concept image and concept definition in mathematics with particular reference to limits and continuity,” Educational studies in mathematics ,12 , 151-169 (1981). Our requirement of coherence, however, distinguishes the two notions.