Search

The article presents a partial dossier on distinguishing between handwritten zero and the letter "oh." Most standard typewriters make no distinction between the "oh" and the zero. In fact, some do not have a key for the zero, relying upon the capital "oh" instead. This is a convention rooted in time. A great deal of handset type and some typewriters differentiate by making the "oh" fatter and rounder while the zero remains a narrow oval. Some fonts have distinguished even more by making the "oh" squarish. Such a difference in character width affords partial distinction; it requires a size discrimination from the reader which requires more concentration than graphic discrimination. The slash has been used to distinguish between the "oh" and the zero. The only problem is that users have been inconsistent in deciding which of the two should be slashed. It is the existing and preferred practice that, on devices such as printers and typewriters, the character shapes for zero and oh be sufficiently different and distinguishable.

This paper describes how some of the semantics of ALGOL 60 can be formalized by establishing a correspondence between expressions of ALGOL 60 and expressions in a modified form of Church's λ-notation. First a model for computer languages and computer behavior is described, based on the notions of functional application and functional abstraction, but also having analogues for imperative language features. Then this model is used as an "abstract object language" into which ALGOL 60 is mapped. Many of ALGOL 60's features emerge as particular arrangements of a small number of structural rules, suggesting new classifications and generalizations. The correspondence is first described informally, mainly by illustrations. The second part of the paper gives a formal description, i.e. an "abstract compiler" into the "abstract object language." This is itself presented in a "purely functional" notation, that is one using only application and abstraction. [ABSTRACT FROM AUTHOR]

An economical method of producing both hard copy and projection forms of text, without duplication of effort. [ABSTRACT FROM AUTHOR]

Presents a letter to the editor in response to the article "Time-sharing on Computers," by R. M. Fano and F. J. Corbató in the September 1966 issue.