IN THE MEMORY OF LINUS PAULING. PARSIMONY. N. L. Smirnova, Moscow State University, Geological Department, Vorobyevy Gory, 119899, Moscow, Russia

Parsimony is one of the universal laws of nature. L. Pauling published five well known rules by him in 1929. He gave the name "parsimony" to the fifth rule which reads: the number of essentially different kinds of constituents in the crystal tends to be small. The attitude of scientists towards this rule is different: some of them decline it (N. V. Belov, V. S. Urusov, 1991), some ignore it (F. Libau, 1988, F. Wells, 1987, L. Pauling in his later publications), some refer to it without comments (B.F. Ormont, 1950, T. Penkal, 1974) some consider it to be less universal than four remaining rules (J. B. Boky, 1971), some apply it to intermetallic structures (F. Laves, 1939), some use it to simulate the structure of inorganic compounds (N. L. Smirnova, 1952 and later publications, V. S. Urusov, L. A. Dubrovinskaya, L. S. Dubrovinsky, 1990) some consider it as an universal law, small numbers being ranged from 1 to 4 (N. L. Smirnova, 1971); in case of a strict parsimony the ancestor should be determined, in case of mild parsimony - members of series (N. L. Smirnova, 1952, 1956 etc.) a more precise definition reads: the number of essentially different kinds of substituents (at least for one of them tends to be small (N. L. Smirnova, 1993). The rule suggests an estimation using four qualitative characteristics, as well as the largest frequency of 1-4-ary combinations. The parsimony rule has been established for formulas of different kinds: positional formulas for structural types and classes, for sfdp formulas (N. L. Smirnova,1993, 1994) for types of the atomic environment (J. L. C. Daams, P. V. Villars), for properties (N. L. Smirnova, 1995, 1996).