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ical notation that permitted the expression of concepts and
methods in a very compact and unambiguous way. Of course,
he was aware that similar ideas, such as those at the foundation
of symbolic logic, had been powering modern mathematics and
physics for quite some time. The novelty of Iverson's approach
was to view notation not only as a formal language for doing
applied mathematics - that is, for defining and proving proper-
ties of mathematical procedures of interest to a scientist - but
also as a programming language whose sentences could be used
to implement these procedures and to execute them on a com-
puter. In short, what Iverson was searching for was a notation
system in which the descriptive and analytical power of a math-
ematical language could naturally coexist with the executability
and universality of a programming language. In his 1979
ACM
Turing Award lecture, Iverson summarized this in the following
way: “The advantages of executability and universality found in
programming languages can be effectively combined, in a single
coherent language, with the advantages offered by mathemat-
ical notation.”
4
Unable to convert his teaching position at Harvard into a
tenured appointment, Iverson moved to
IBM
in 1960, where
he continued to work on his notation system with a group of
people that included Philip Abrams, Lawrence Breed, and Adin
Falkoff. In 1965, their work resulted in the first complete im-
plementation of Iverson's notation as a programming language
done by Abrams and Breed. The language itself was baptized
“
APL
” by Falkoff, who derived the name from the title of
Iverson's book
A Programming Language
, published in 1962. In
this topic, Iverson described the principles and applications of
his notation system.
After some dispute with
IBM
's Applied Physics Lab, which
objected to the acronym, the name “
APL
” was cleared by
IBM
and would soon mesmerize a large number of computer pro-
