August 1975 - Vol. 18 No. 8
Features
On the external storage fragmentation produced by first-fit and best-fit allocation strategies
Published comparisons of the external fragmentation produced by first-fit and best-fit memory allocation have not been consistent. Through simulation, a series of…
Deterministic parsing of ambiguous grammars
Methods of describing the syntax of programming languages in ways that are more flexible and natural than conventional BNF descriptions are considered. These methods…
Guarded commands, nondeterminacy and formal derivation of programs
So-called “guarded commands” are introduced as a building block for alternative and repetitive constructs that allow nondeterministic program components for…
Remark on stably updating mean and standard deviation of data
Although not published as a numbered algorithm, Hanson's article “Stably Updating Mean and Standard Deviation of Data” in the January, 1975, issue of…
Interactive consulting via natural language
Interactive programming systems often contain help commands to give the programmer on-line instruction regarding the use of the various systems commands. It is argued…
Comments on a paper by T.C. Chen and I.T. Ho
Tien Chi Chen and Irving T. Ho in their paper “Storage-Efficient Representation of Decimal Data” [1] present a scheme for the compression of numbers stored in…
Consecutive storage of relevant records with redundancy
This paper studies the properties of a new class of file organizations (CRWR) where records relevant to every query are stored in consecutive storage locations but the…
Multiple byte processing with full-word instructions
A method is described which allows parallel processing of packed data items using only ordinary full-word computer instructions, even though the processing requires…
Combining decision rules in a decision table
The techniques for minimizing logic circuits are applied to the simplification of decision tables by the combining of decision rules. This method is logically equivalent…