Evolution of the Concept of Synthesis Strategy in the COSYMA System: Introduction of the Synthesis Invariant

COSYMA is a program for the computer‐assisted design of organic synthesis; its aim is to propose strategies for the synthesis of given compounds. These strategies are automatically learnt from global syntheses described in the literature, and adapted to the specifics of the target molecule. This paper describes an evolution of the formalization of synthesis strategy by taking into account untouched fragments, and the resulting improvement of the COSYMA program.