980 research outputs found
The Finite and the Infinite in Frege's Grundgesetze der Arithmetik
Discusses Frege's formal definitions and characterizations of infinite and finite sets. Speculates that Frege might have discovered the "oddity" in Dedekind's famous proof that all infinite sets are Dedekind infinite and, in doing so, stumbled across an axiom of countable choice
Infinity
This essay surveys the different types of infinity that occur in pure and applied mathematics, with emphasis on: 1. the contrast between potential infinity and actual infinity; 2. Cantor's distinction between transfinite sets and absolute infinity; 3. the constructivist view of infinite quantifiers and the meaning of constructive proof; 4. the concept of feasibility and the philosophical problems surrounding feasible arithmetic; 5. Zeno's paradoxes and modern paradoxes of physical infinity involving supertasks
The ontology of number
What is a number? Answering this will answer questions about its philosophical foundations - rational numbers, the complex numbers, imaginary numbers. If we are to write or talk about something, it is helpful to know whether it exists, how it exists, and why it exists, just from a common-sense point of view [Quine, 1948, p. 6]. Generally, there does not seem to be any disagreement among mathematicians, scientists, and logicians about numbers existing in some way, but currently, in the mainstream arena only definitions, descriptions of properties, and effects are presented as evidence. Enough historical description of numbers in history provides an empirical basis of number, although a case can be made that numbers do not exist by themselves empirically. Correspondingly, numbers exist as abstractions. All the while, though, these "descriptions" beg the question of what numbers are ontologically. Advocates for numbers being the ultimate reality have the problem of wrestling with the nature of reality. I start on the road to discovering the ontology of number by looking at where people have talked about numbers as already existing: history. Of course, we need to know not only what ontology is but the problems of identifying one, leading to the selection between metaphysics and provisional approaches. While we seem to be dimensionally limited, at least we can identify a more suitable bootstrapping ontology than mere definitions, leading us to the unity of opposites. The rest of the paper details how this is done and modifies Peano's Postulates
Counting inequivalent monotone Boolean functions
Monotone Boolean functions (MBFs) are Boolean functions satisfying the monotonicity condition for any . The number of MBFs in n variables is
known as the th Dedekind number. It is a longstanding computational
challenge to determine these numbers exactly - these values are only known for
at most 8. Two monotone Boolean functions are inequivalent if one can be
obtained from the other by renaming the variables. The number of inequivalent
MBFs in variables was known only for up to . In this paper we
propose a strategy to count inequivalent MBF's by breaking the calculation into
parts based on the profiles of these functions. As a result we are able to
compute the number of inequivalent MBFs in 7 variables. The number obtained is
490013148
A Burgessian critique of nominalistic tendencies in contemporary mathematics and its historiography
We analyze the developments in mathematical rigor from the viewpoint of a
Burgessian critique of nominalistic reconstructions. We apply such a critique
to the reconstruction of infinitesimal analysis accomplished through the
efforts of Cantor, Dedekind, and Weierstrass; to the reconstruction of Cauchy's
foundational work associated with the work of Boyer and Grabiner; and to
Bishop's constructivist reconstruction of classical analysis. We examine the
effects of a nominalist disposition on historiography, teaching, and research.Comment: 57 pages; 3 figures. Corrected misprint
For which triangles is Pick's formula almost correct?
We present an intriguing question about lattice points in triangles where
Pick's formula is "almost correct". The question has its origin in knot theory,
but its statement is purely combinatorial. After more than 30 years the
topological question was recently solved, but the lattice point problem is
still open.Comment: 6 pages; v2 more background information; v3 update of recent
developments; v4 final revision and reformattin
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