INDEX logic

Coordinate Indexing and Boolean Logic. Three methods of indexing have been prominent in the chemical Hterature in recent times. The first, articulated indexing, has been used in printed Chemicaly hstracts subject indexes from their earliest days until well into the 1990s. A number of important concepts are identified as permissible index entries, including specific compounds, material types, reactions, and processes. One or more modifying statements foUow each basic index entry. Thus, eg. 

In the earliest days of on-line databases, all three indexing types coUapsed into the third. Using older manual tools, it was difficult to coordinate more than two or three concepts, but the computer made that easier. Each concept in a search can be represented by a string of synonyms or alternatives, and searching can be done for two such parameters or more. Thus, Boolean logic expressions can easily be constmcted as follows ... 

Although we have no way of determining the moisture content of the individual components, it is not difficult to measure a property which is directly related to it and is common to all the components—the equilibrium pressure of water vapor. It seems logical, therefore, to use it as an index of moisture, as suggested by Makower and Myers (20). 

The NSS concept corresponds to an operator attached to an arbitrary number of nested sums. In other words, a NSS represents a set of summation symbols where the number of them can be variable. In a general notation one can write a NSS as E (j=i,f,s,L) where the meaning of this convention corresponds to perform all the sums involved in the generation of all the possible values of the index vector j under the fulfillment of the set of logical expressions collected in the components of the vector L. The elements of the vector j have the following limits ... 

In a multi-reactant system where no identification of an unstable product was possible, one of the reactants had to be selected as primary reactant to prepare and index the main entry, with the other material(s) as secondary reactant(s). No strictly logical basis of choice for this is obvious. 

In principle, it would be logical to combine plots of the buffer index curves of each of the buffer components of milk and thus obtain a plot which could be compared with that actually found for milk. It is not difficult, of course, to conclude that the principal buffer components are phosphate, citrate, bicarbonate, and proteins, but quantitative assignment of the buffer capacity to these components proves to be rather difficult. This problem arises primarily from the presence of calcium and magnesium in the system. These alkaline earths are present as free ions as soluble, undissociated complexes with phosphates, citrate, and casein and as colloidal phosphates associated with casein. Thus precise definition of the ionic equilibria in milk becomes rather complicated. It is difficult to obtain ratios for the various physical states of some of the components, even in simple systems. Some concentrations must be calculated from the dissociation constants, whose... 

In 1928, A. M. Patterson, later one of the authors of the Ring Index, wrote Any attempt to construct a strictly logical system of names for the large number of parent ring systems now known seems impractical, at least as far as common use is concerned. 7 This sentiment is no less applicable today. For heterocycles in particular, the number of trivial names in current use is large. In the 1969 IUPAC Rules,6 63 trivially named heterocyclic skeletons with various degrees of unsaturation are listed, with a further 25 in the 1973 Tentative Rules (Section D).8 Chemical Abstracts nomenclature rules list 83 such skeletons with maximum unsaturation, many of which are not included by IUPAC. Thus, although systematic operations are often required to derive the name of a heterocyclic skeleton, the parent names to which these operations are applied are frequently trivial. 

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