OFFSET
0,4
COMMENTS
We define the "inversion of variables", i, by (i.f)(x1,...,xn)=1+f(1+x1,...,1+xn). Note that {i,identity function} is a group. It turns out that if f is a monotone function, then i.f is also a monotone function. f is equivalent to g if f=g or f=i.g.
EXAMPLE
a(2)=1 because f(x1,x2)=x1x2 is equivalent to g(x1,x2)=x1+x2+x1x2 and there are no more monotone Boolean nondegenerate functions of 2 variables.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Alan Veliz-Cuba (alanavc(AT)vt.edu), Jun 16 2006
STATUS
approved