Classification of Boolean functions in dimension 7


This page reports the numerical experiments related to the classification of the Boolean Functions in less than 7 variables that we computed in April 2022. In this continuation of the experiment, we provide more results and all the details presented at the BFA-2022 conference on Boolean functions and their applications.


Definitions

Let m be a positive integer. The space of Boolean functions from GF(2)^m into GF(2) is denoted by RM(k,m). This notation comes from coding theory, it is the Reed-Muller code of order k in m variables. The affine group AG(2, m) acts over the spaces RM(k,m), and thus on RM(k,m)/RM(r,m) when r<=k. Two Boolean functions f and g are said to be equivalent modulo RM(r, m) if there exists an affine transformation A in AG(2,m) such that

g = f o A modulo RM(r,m)

Affine group

The affine group has order :

#AG(2, m) = 2^m (2^m - 1)(2^m - 2)...(2^m - 2^(m-1) )

it can be generated by three transformations : the shift S, a transvection T and a nontrivial translation U. The affine group acts over RM(k,m) and also over B(s,t,m) := RM(t,m)/RM(s-1,m). A formula for the rank n(s, t, m) of the action of AG(2,m) over B(s,t,m) was determined by Xiang-Dong Hou,

AGL(m, 2) Acting on R(r, m)/R(s, m), journal of algebra 171/3 (1995)
It satisfies :
n(s, t, m ) = n( m-t, m - s, m)

Objectives

s/t 1 2 3 4 5 6 7
0 3 12 3486 1013.51019.8 1021.91022.2
1 2 8 1890 1013.1 1019.5 1021.6 1021.9
2 4 179 10 11.0 1017.3 1019.5 1019.8
3 12 68443 1011.01013.11013.5
4 12 179 1890 3486
5 4 8 12
6 2 3
7 2
Class numbers of B(s,t,7)

The objective of this numerical experiment consists in providing the classifications of B(s,t,7) = RM(t,7)/RM(s-1,7) for all the reasonable parameters s and t.

Methodology - Result - Application

The details are given in the following
[ slides ] [ abstract ] [ article ] [ data ] [ clip ]

As a baby example, we computed the full classification of 6-bits function in 2 minutes, there are 7888299 classes...

[ 6-bit functions modulo GF(2) ]



Valérie Gillot, Philippe Langevin,
imath,
last modification : autumn 2022.