to this trend by developing the PSI machine, and most importantly by developing ESP. 
ESP was the first programming language that combined both the logic programming 
paradigm as embodied in Prolog and the object oriented programming paradigm. The 
flexibility of the language was clearly demonstrated by programming the operating sys-
tem of PSI and developing a number of tools for knowledge representation and natural 
language processing. 

ICOT played a central role in the development of programming languages for par-
allel symbolic computing. The design of GHC was certainly a very important step in 
the development of concurrent logic programming languages. 

ICOT has contributed considerably to the implementation technology of program-
ming languages on parallel architectures. Techniques for memory management like the 
MRB scheme and parallel garbage collection on cluster basis, were certainly innovative 
techniques developed by ICOT. 

ICOT has also contributed considerably to the development of constraint logic pro-
gramming by for example, the work on CIL and CAL. 

The development of PIMOS is the first large scale operating system for parallel 
computers. 

ICOT demonestrated, beyond doubt, the usefulness of parallel processing in sym-
bolic and highly irregular computations. 

On the negative side 

ICOT invested a lot of effort trying to compile the programming paradigms of PROLOG 
to KL1, but one must say that these efforts have only partially succeeded. Research 
done by outside researchers has shown that it is possible to combine Prolog and GHC 
(a good example is the work done at SICS on Andorra). However, the results came 
too late to be exploited within the remaining time allocated to the project. This is 
very unfortunate since a lot of ICOT's early research on natural language processing 
and constraints was based on Prolog and could not be exploited effectively when the 
project moved from ESP to KL1. Moreover there is some doubt about the flexibility 
of the communication structures of KL1. 

Due to the lack of time the results of ICOT on knowledge representation and knowl-
edge bases remain unevaluated by the outside research community. 

It is questionable whether the architectures produced by the project are adequate 
for efficiently implementing languages like KL1. The most important issue is the lack 
of support of global address spaces, and multiple-users address spaces in the hardware. 
It is widely accepted by researchers in computer architecture that global address space 


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