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On the Elimination of Procedure Nestings. In ALGOL-like programming languages with procedures there are several properties of programs concerning procedures that may be used to improve resp. optimise the performance of the runtime system. In these considerations problems very soon arise, because in general one has to discuss programs with an arbitrary nesting of procedure declarations. This paper shows that an arbitrary ALGOL 60-program can be transformed into an ALGOL 60-program which has a maximal procedure nesting 2, and both programs define the same input-output function. In order to prove this property a new notion for equivalence of ALGOL-like programs with procedures is introduced.Zur Elimination von Prozedurschachtelungen. In ALGOL-~ihnlichen Programmiersprachen mit Prozeduren gibt es im Zusammenhang mit diesen Prozeduren eiue Reihe yon Programmeigenschaften, die zu einer Verbesserung des Laufzeitsystems benutzt werden k6nnen. Bei solchen 13berlegungen treten jedoch h~iufig Probleme auf, da man Programme mit beliebigen Prozedurschachtelungen betrachten muB. Es wird nun gezeigt, dab sich beliebige ALGOL-60-Programme in funktional aquivalente Programme mit einer maximalen Prozedurschachtelungstiefe 2 transforrnieren lassen. Als HilfsmitteI wird hierzu ein neuer Aquivalenzbegriff fiir ALGOL-~ihnliche Programme mit Prozeduren eingefiihrt.

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The goal of the paper is to show that copy-rule semantics can handle higher order functionals in the sence of FUNARGs in LISP. A language LISP/N, which is derived from pure LISP, is introduced and the semantics are defined without reference to an interpreter; its definition is essentially based on a copy-rule for LISP/N.

Steady-state VEPs were recorded and analyzed using laser interference gratings in Maxwellian view as a pattern reversal stimulus and Fourier analysis. Two groups of 51 and 36 persons served as normal subjects in this study. The object of interest was the relationship of phase to spatial frequency (2-30 cycles/deg), contrast (0.1-0.99), and pattern reversal rate (2-31 rps). The phase shows a weak increase of some 10° with decreasing contrast. It remains constant with spatial frequency until local flicker effects lead to a small increase for coarse gratings (2 cycles/deg). This phase behavior appears to be approximately constant in contrast to phase and latency results of other authors,1,2 who obtained large variations as a function of spatial frequency and contrast with VEP stimulation involving the MTF of the eye. We find constant phase both with gratings offered in isolation and with simultaneous multifrequency stimulation using superimposed laser gratings. The reversal rate was varied from 2 to 31 rps in 0.5-rps steps. The extremely linear phase relationship enables a precise latency estimation (t = 1/360 × dϕ/df). Estimated latencies correspond well with P 2 latencies. For example, estimates were 113.6 ms for a 2-cycles/deg grating, 104.9 ms for18 cycles/deg, and a value of 105.6 ms for a 30-cycles/deg grating.

Functional programming languages based on the lambda calculus provide a powerful programming tool. Much of this power derives from the ability to use higher order functions, that means functions having either functional arguments or a functional result. However, attempts to implement such higher order functions without any restrictions have always been expensive, both in storage and time (e.g. [Bo/We]). ALGOL-like languages only have functions with functional arguments (e.g. ALGOL 60 or, with some mode restrictions, PASCAL) and a run time stack can be used for managing function and procedure calls. Using Dijkstra's “display-technique” we can obtain a simple and efficient implementation.

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