Continue intro a little

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Théophile Bastian 2017-08-19 10:56:04 +02:00
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\section{Introduction} \section{Introduction}
In the previous years, verification and proved software has gathered an
increasing interest in the computer science community, as people realised how
hard bugs are to track down. But hardware bugs are even more tedious to find
and fix, and can easily lead to disastrous consequences, as those cannot be
patched on existing hardware. For instance, the well-known Pentium
``\textsc{fdiv}'' bug~\ref{pratt1995fdiv} that affected a large number of
Pentium processors lead to wrong results for some floating point divisions.
Intel had to replace \todo{how many?} CPUs, leading to a loss of \todo{how
much?}. Even recently, the Skylake and Kiby Lake \todo{(?)} hyperthreading bug
had to be patched using microcode, loosing performance and reliability.
To avoid such disasters, the industry nowadays uses a wide range of techniques
to catch bugs as early as possible -- which, hopefully, is before the product's
release date. Among those are \todo{list + cite}, but also proved hardware. On
circuits as complex as processors, usually, only sub-components are proved
correct in a specified context -- that should, but is not proved to, be
respected by the other parts of the circuit. Yet, this trade-off between proved
correctness and engineer's work time already gives a pretty good confidence in
the circuit.
In this context, Carl Seger was one of the \todo{the?} main developer of FL
\todo{(?, acronym?)} at Intel, a functional programming language integrating
many features useful to get insights of a circuit, testing it and proving it.
Among other features, it includes a ``search and replace'' feature, which can
search every occurrence of a given gates pattern in a circuit, and replace it
by some other gates pattern, proved observationally equivalent.\\
Time has proved this method very efficient to design circuits: this way, one
can start from an inefficient, yet simple circuit, prove it, and then refine it
into an equivalent, yet efficient one, through proved transformations. It is
also possible to go the other way, and start with an optimized circuit, hard to
understand, and make it easier to understand to work more efficiently.
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\section{Context \& AST} \section{Context \& AST}
\todo{Rename this section}\\ \todo{Rename this section}\\