The intermediate value theorem in constructive mathematics without choice
نویسندگان
چکیده
منابع مشابه
Constructive mathematics without choice
What becomes of constructive constructive mathematics without the axiom of (countable) choice? Using illustrations from a variety of areas, it is argued that it becomes better. Despite the apparent unanimity among schools of constructive mathematics with respect to the acceptance of the countable axiom of choice, I believe it to be one of the central problems, or mysteries, of constructive math...
متن کاملThe binary expansion and the intermediate value theorem in constructive reverse mathematics
We introduce the notion of a convex tree. We show that the binary expansion for real numbers in the unit interval (BE) is equivalent to weak König lemma (WKL) for trees having at most two nodes at each level, and we prove that the intermediate value theorem (IVT) is equivalent to WKL for convex trees, in the framework of constructive reverse mathematics.
متن کاملThe Fundamental Theorem of Algebra: a Constructive Development without Choice
Is it reasonable to do constructive mathematics without the axiom of countable choice? Serious schools of constructive mathematics all assume it one way or another, but the arguments for it are not compelling. The fundamental theorem of algebra will serve as an example of where countable choice comes into play and how to proceed in its absence. Along the way, a notion of a complete metric space...
متن کاملThe Vitali covering theorem in constructive mathematics
This paper investigates the Vitali Covering Theorem from various constructive angles. A Vitali Cover of a metric space is a cover such that for every point there exists an arbitrarily small element of the cover containing this point. The Vitali Covering Theorem now states, that for any Vitali Cover one can find a finite family of pairwise disjoint sets in the Vitali Cover that cover the entire ...
متن کاملPerhaps the Intermediate Value Theorem
In the context of intuitionistic real analysis, we introduce the set F consisting of all continuous functions φ from [0, 1] to R such that φ(0) = 0 and φ(1) = 1. We let I0 be the set of all φ in F for which we may find x in [0, 1] such that φ(x) = 12 . It is well-known that there are functions in F that we can not prove to belong to I0, and that, with the help of Brouwer’s Continuity Principle ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Annals of Pure and Applied Logic
سال: 2012
ISSN: 0168-0072
DOI: 10.1016/j.apal.2011.12.026