منابع مشابه
Cohesive Sets: Countable and Uncountable
We show that many uncountable admissible ordinals (including some cardinals) as well as all countable admissible ordinals have cohesive subsets. Exactly which cardinals have cohesive subsets, however, is shown to depend on set-theoretic assumptions such as V=L or a large cardinal axiom. The study of recursion theory on the ordinals was initiated by Takeuti and then generalized by several others...
متن کاملFountain rainbows.
We present the first measurements of radiance spectra of rainbows. The bows on two sunny days (3 and 6 June 2008) were produced by the fountain in the Parque de las Ciencias, Granada, Spain, that consists of a rectangular perimeter of 40 spray nozzles. Optical thickness of the spray from each nozzle was approximately 0.5. Spectral purity of the primary bow was highest for orange and blue, reach...
متن کاملRainbows and fogbows.
The optics of rainbows and fogbows is investigated theoretically for monodisperse drops using Mie theory. Included in the calculations are a realistic solar illumination spectrum and the finite size of the sun. Drop sizes range from 3 to 300 microm (3800 > X > 38). Results are presented on the location, width, contrast, polarization, and color of both primary and secondary rainbows. Particular ...
متن کاملRainbows in the Hypercube
Let Qn be a hypercube of dimension n, that is, a graph whose vertices are binary n-tuples and two vertices are adjacent iff the corresponding n-tuples differ in exactly one position. An edge coloring of a graph H is called rainbow if no two edges of H have the same color. Let f(G, H) be the largest number of colors such that there exists an edge coloring of G with f(G, H) colors such that no su...
متن کاملThe Calculus of Rainbows
The geometry of reflection and refraction explains the apparent position of a rainbow relative to the sun, and calculus shows why light is concentrated in the rainbow. Exercises include the derivation of Snell’s Law and the Law of Reflection, an explanation for the different colors in the rainbow, and an exploration of secondary and tertiary rainbows. This is intended as a one-hour lecture for ...
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ژورنال
عنوان ژورنال: Annals of Pure and Applied Logic
سال: 2014
ISSN: 0168-0072
DOI: 10.1016/j.apal.2013.06.002