Does two's complement arithmetic produce a field isomorphic to GF(2^n)?

Emmanuel Giles

Emmanuel Giles

Answered question

2022-11-23

Does two's complement arithmetic produce a field isomorphic to G F ( 2 n ?
From what I understand, we have these two isomorphisms:
(TC,+) is isomorphic to the cyclic group Z / 2 n Z .
(TC,∗) is isomorphic to the multiplicative group of polynomials.
If this is correct, can we conclude that two's complement arithmetic produces a finite field isomorphic to G F ( 2 n ?
If not, what algebraic structure, if any, does two's complement representation and arithmetic produce? Because there just seems to be something there.

Answer & Explanation

iletsa2ym

iletsa2ym

Beginner2022-11-24Added 22 answers

Step 1
The additive group is already a problem, since for G F ( 2 n ) it is ( Z / 2 Z ) n , not Z / 2 n Z .
In fact, it cannot be a field, since it has zero-divisors: 2 k 2 n k = 0.Step 2
Two's complement arithmetic is isomorphic to the quotient in your question, Z / 2 n Z , but not only as groups, but as rings, that is, with multiplication too. This structure is rarely a field, through (only if n = 1).

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