The Inside and Outside of E

number of extensions both for preprocessing and for the proof search proper. While the implementation borrows many proven techniques
from older implementations, E has also pioneered novel approaches, particularly in data representation, indexing, and search control.
However, while E is rather unique on the inside, it very much tries to conform to (or set) standards on the outside.
E is implemented in ANSI/ISO C and uses (a minimal subset) of the POSIX specification for additional operating system services.
As a consequence, it is widely portable and easy to install on nearly any modern UNIX-like operating system, and even on
Windows (using CygWin). E itself can read and write data in the LOP/PCL, TPTP-2 and TPTP-3 formats. It also uses the SZS
output ontology to describe the result of the proof search. As a consequence, it plays well with other systems and has been integrated
into several larger systems.