Reactions and Transformations - Design and Use of Relational Databases in Chemistry - page 107

symbol, each reactant and product can have a canonical representation.
The overall reaction SMILES also has a canonical representation that is
not necessarily the combination of the canonical SMILES of the reactants
and products. The SQL extension function cansmiles correctly computes
the canonical reaction SMILES. This can be used as a unique representa-
tion of a reaction in the same way that a regular SMILES can be used as a
unique representation of a chemical structure.
Because SMIRKS is a combination of SMILES and SMARTS and
because there is no canonical representation of SMARTS, there is no
canonical representation of SMIRKS. SMARTS can be considered as a set
of instructions on how to match substructures of SMILES. SMIRKS can
similarly be considered as a set of instructions on how to identify reactive
atoms and combine or alter them in order to carry out a specific transfor-
mation of a set of SMILES.
References
1. SMIRKS tutorial. 2007. http://www.daylight.com/dayhtml_tutorials/lan-
guages/smirks/index.html (accessed April 18, 2008).
2. Yadav M., Kelley, B.P. and Silverman, S.M. 2004. The potential of a chemical
graph transformation system. In Graph Transformations: ICGT 2004 Proceedings ,
ed. H., Ehrig, G., Engels, F., Parisi-Presicce and G., Rozenberg, 83-95. Berlin:
Springer Verlag.
3. Ugi, I., 1962. The α-addition of immonium ions and anions to isonitriles
accompanied by secondary reactions. Angewandte Chemie International Edition
in English 1(1):8-21.