Strictly speaking these are two different questions:


Actual physical representation: this isn't visible at the Prolog level, and therefore the standard quite rightly has nothing to say about it.  Note that many Prolog systems have two or more internal representations (e.g. two's complement fixed size and sign+magnitude bignums) but present a single integer type to the programmer.
Results of bitwise operations: while the standard defines these operations, it leaves much of their behaviour implementation defined.  This is a consequence of (a) not having a way to specify the width of a bit pattern, and (b) not committing to a specific mapping between negative numbers and bit patterns.


This not only means that all bitwise operations on negative numbers are officially not portable, but also has the curious effect that the result of bitwise negation is totally implementation-defined (even for positive arguments):  Y is \1 could legally give -2, 268435454, 2147483646, 9223372036854775806, etc. All you know is that negating twice returns the original number.

In practice, fortunately, there seems to be a consensus towards "The bitwise arithmetic operations behave as if operating on an unlimited length two's complement representation".

Representation of negative integers
should I pick Ubuntu 12.04.2 LTS or 12.10 for my home machine?

I know that Ubuntu 12.04 is LTS but 12.10 is newer.

But what should I pick now?

Can I use Gnome 3 Shell (apt-get install gnome-shell) without any problems in Ubuntu or is it recommend to use Unity?

Greetings,
Majestro
