Abelian Exponentiation
Unlike addition and multiplication, normal exponentiation is not commutative:
a+b=b+a
a*b=b*a
but
a^b≠b^a
However, it is a relatively simple matter to define an operation similar to normal exponentiation that
is commutative:
normal exponentiation:
a^n=a*a*a*...a
1+1+1+...1=n
Abelian exponentiation (where # is the symbol for it):
a#n=a*a*a*...a
2*2*2*...2=n
or
a#n=2^{(log2a)*(log2n)}
The positive real numbers (R+) form an Abelian group under Abelian exponentiation (#) and, (R+,*,#) forms
a field which is isomorphic to the real field (R,+,*).
Proof that Abelian exponentiation forms and Abelian group:
Associative: for each a, b, c in R+,
(a#b)#c=a#(b#c)
Proof:
(a#b)#c=[2^{(log2a)*(log2b)}]#c=
2^[[log2[2^{(log2a)*(log2b)}]]*(log2c)]=
2^{(log2a)*(log2b)*(log2c)}
and
a#(b#c)=a#[2^{(log2b)*(log2c)}]=
2^[(log2a)*[log2[2^{log2b)*(log2c)}]]]=
2^{(log2a)*(log2b)*(log2c)}
Identity: there exists a unique elememt, 2, in R+ such that for each a in R+,
a#2=a
Proof:
a#2 = 2^{(log2a)*(log22)}= 2^(log2a)=a
Inverse element: corresponding to each elelment a in R+ there is an inverse element 2^{1/(log2a)} (a≠1)
in R+ such that
[2^{1/(log2a)}]#a=2
Proof:
[2^{1/(log2a)}]#a=
2^[[log2[2^{1/(log2a)}]]*(log2a)]=
2^[{1/(log2a)}*(log2a)]=2^1=2
Commutative: for each a, b in R+,
a#b=b#a
Proof:
a#b=2^{(log2a)*(log2b)}
and
b#a=2^{(log2b)*(log2a)}=2^{(log2a)*(log2b)}
With the following distribution postulate for Abelian exponentiation, the operations of multiplication
and Abelian exponentiation over R+ form a field:
Distributive (with respect to multiplication): for each a, b, c in R+,
a#(b*c)=(a#b)*(a#c)
Proof:
a#(b*c)=2^[(log2a)*{log2(b*c)}]=
2^[(log2a)*{(log2b)+(log2c)}]
and
(a#b)*(a#c)=
[2^{(log2a)*(log2b)}]*[2^{(log2a)*(log2c)}]=
2^[{(log2a)*(log2b)}+{(log2a)*(log2c)}]=
2^[(log2a)*{(log2b)+(log2c)}]
This field (R+,*,#) is isomorphic with the real field (R,+,*). The isomorphism is indicated by the
existence of a 1 to 1 map (R --> R+ : f(r) = 2^r) such that for all r1, r2 in R:
a) 2^(r1+r2)=(2^r1)*(2^r2);
b) 2^(r1*r2)=(2^r1)#(2^r2).
Comments
First, it should be noted that the choice of 2 as the identity element of Abelian exponentiation was
somewhat arbitrary. Any positive real number (not equal to the multiplicative identity -- 1, in normal
multiplication) could
have been used. In the base 10 numbering system, another logical choice for the identity element
might be 10. Second, while there may be some degree of uncomfortability with the fact that there can
be more than 1 possibility for the identity element, it must be pointed out that this is also true of
both addition and multiplication, too (see Mathematical Relativity --
http://mysite.verizon.net/reriker/re03001.html).