453 research outputs found
The real numbers - a survey of constructions
We present a comprehensive survey of constructions of the real numbers (from
either the rationals or the integers) in a unified fashion, thus providing an
overview of most (if not all) known constructions ranging from the earliest
attempts to recent results, and allowing for a simple comparison-at-a-glance
between different constructions
The real field with an irrational power function and a dense multiplicative subgroup
This paper provides a first example of a model theoretically well behaved
structure consisting of a proper o-minimal expansion of the real field and a
dense multiplicative subgroup of finite rank. Under certain Schanuel
conditions, a quantifier elimination result will be shown for the real field
with an irrational power function and a dense multiplicative subgroup of finite
rank whose elements are algebraic over the field generated by the irrational
power. Moreover, every open set definable in this structure is already
definable in the reduct given by just the real field and the irrational power
function
Expansion of a semi-bounded o-minimal structure by a geometric progression
We demonstrate that an expansion of a semi-bounded o-minimal expansion of the
ordered group of reals by an increasing geometric progression is locally
o-minimal
Extending du Bois-Reymond's Infinitesimal and Infinitary Calculus Theory
The discovery of the infinite integer leads to a partition between finite and
infinite numbers. Construction of an infinitesimal and infinitary number
system, the Gossamer numbers. Du Bois-Reymond's much-greater-than relations and
little-o/big-O defined with the Gossamer number system, and the relations
algebra is explored. A comparison of function algebra is developed. A transfer
principle more general than Non-Standard-Analysis is developed, hence a
two-tier system of calculus is described. Non-reversible arithmetic is proved,
and found to be the key to this calculus and other theory. Finally sequences
are partitioned between finite and infinite intervals.Comment: Resubmission of 6 other submissions. 99 page
Structure theorems for o-minimal expansions of groups
Let R be an o-minimal expansion of an ordered group (R,0,1,+,<) with distinguished positive element 1. We first prove that the following are equivalent: (1) R is semi-bounded, (2) R has no poles, (3) R cannot define a real closed field with domain R and order <, (4) R is eventually linear and (5) every R-definable set is a finite union of cones. As a corollary we get that Th(R) has quantifier elimination and universal axiomatization in the language with symbols for the ordered group operations, bounded R-definable sets and a symbol for each definable endomorphism of the group (R,0,+)
The reals as rational Cauchy filters
We present a detailed and elementary construction of the real numbers from
the rational numbers a la Bourbaki. The real numbers are defined to be the set
of all minimal Cauchy filters in (where the Cauchy condition is
defined in terms of the absolute value function on ) and are proven
directly, without employing any of the techniques of uniform spaces, to form a
complete ordered field. The construction can be seen as a variant of Bachmann's
construction by means of nested rational intervals, allowing for a canonical
choice of representatives
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