# Constructible

### Some articles on constructible:

Compass And Straightedge Constructions - Constructible Angles
... is a bijection between the angles that are constructible and the points that are constructible on any constructible circle ... The angles that are constructible form an abelian group under addition modulo 2π (which corresponds to multiplication of the points on the unit circle viewed as complex numbers) ... The angles that are constructible are exactly those whose tangent (or equivalently, sine or cosine) is constructible as a number ...
Lefschetz Hyperplane Theorem - The Lefschetz Theorem in Other Cohomology Theories
... The motivation behind Artin and Grothendieck's proof for constructible sheaves was to give a proof that could be adapted to the setting of étale and -adic cohomology ... Up to some restrictions on the constructible sheaf, the Lefschetz theorem remains true for constructible sheaves in positive characteristic ...
Constructible Polygon
... In mathematics, a constructible polygon is a regular polygon that can be constructed with compass and straightedge ... For example, a regular pentagon is constructible with compass and straightedge while a regular heptagon is not ...
Space Hierarchy Theorem - Statement
... Formally, a function is space-constructible if and there exists a Turing machine which computes the function in space when starting with an input, where represents a string ... the common functions that we work with are space-constructible, including polynomials, exponents, and logarithms ... For every space-constructible function , there exists a language that is decidable in space but not in space ...
Constructible Polygon - Conditions For Constructibility - Connection To Pascal's Triangle
... are multiples of distinct Fermat primes, and hence 31 constructible odd-sided regular polygons ... composite, so the following rows do not correspond to constructible polygons ... Fermat primes exist, and is therefore unknown how many odd-sided constructible polygons exist ...