Institute of Chemistry, Chemical Research Center,

E-mail: lukovits@cric.chemres.hu

The problem of exhaustive non-redundant generation of graphs of isomers of acyclic alkanes was considered. The compressed adjacency matrix (CAM) technique and the canonical rules of numbering derived previously were used to systematize and simplify the generation procedure. The algorithm generates all trees that are numbered according to the Morgan naming algorithm. Out of these set of codes those corresponding to the maximal Morgan codes - which in fact are the codes of the canonically numbered isomers - must be singled out. The codes are conceived as sentences of a primitive language. New rules were introduced to restrict the set of structures to be generated. The whole selection procedure consists of two consecutive steps: 1. First all sentences (codes) which do not obey to the syntactic rules have to be deleted; 2. After this step semantic rules are used to discard all remaining codes of the underlying structures which violate the "lowest degrees first" (LDF) rule. The procedure is efficient.