Starting with the ordered set Q of rational numbers, Dedekind defined a real number to be an ordered pair (L, R), where L < R, L ∪ R= Q and L, R ≠o. von Neumann later identified each ordinal with the set of all ordinals previously created, so that, 0 = o, 1 = {0}, … , ω = {0, 1, …}, and so on. More recently, Conway [5, 6] discovered that these two methods can be subsumed under a more general construction which leads to an ordered class of numbers embracing the reals and the ordinals as well as many less familiar numbers including -ω, ω/2, 1/ω, (Math) and ω – πt to name only a few. He further showed that the arithmetic of the reals may be extended to the entire class yielding a real-closed ordered field.
[1]
Philip Ehrlich.
Absolutely saturated models
,
1989
.
[2]
Azriel Levy.
Basic set theory
,
1979
.
[3]
Philip Ehrlich,et al.
An alternative construction of Conway's ordered field No
,
1988
.
[4]
J. Conway.
On Numbers and Games
,
1976
.
[5]
William N. Reinhardt,et al.
Ackermann's set theory equals ZF
,
1970
.
[6]
N. L. Alling,et al.
CONWAY'S FIELD OF SURREAL NUMBERS
,
1985
.
[7]
H. Gonshor.
An Introduction to the Theory of Surreal Numbers
,
1986
.