FACTOID # 59: People might eat oats when they're hungry, but people from Hungary don't eat oats.
 
 Home   Encyclopedia   Statistics   Countries A-Z   Flags   Maps   Education   Forum   FAQ   About 
 
WHAT'S NEW
RECENT ARTICLES
More Recent Articles »
 

FACTS & STATISTICS    Simple view

  1. Select countries to view: (hold down Control key and click to select several)

     

     

    Compare:

     

     

  1. Select fact or statistic: (* = graphable)

     

     

     

  2. (OPTIONAL) Compare to statistic: (both need to be graphable)

     

     

     

  3. View result as:

     

       
(OR) SEARCH ALL encyclopedia, stats & forums:   

Encyclopedia > Invertible element


In mathematics, a unit in a ring R is an element u such that there is v in R with

uv = vu = 1R.

That is, u is an invertible element of the multiplicative monoid of R. The units of R form a group U(R) under multiplication, the group of units of R.


The orbits of U(R) acting on R by multiplication are called sets of associates; in other words there is an equivalence relation on R called associatedness such that

r ~ s

means that there is a unit u with r = us. For example in the ring Z of integers n and −n are associates.


Any root of unity is a unit. In algebraic number theory Dirichlet's unit theorem shows the existence of many units in most rings of algebraic integers. For example, we have

(√5 + 2)(√5 − 2) = 1.

In fact that is the source for the unit terminology — which shouldn't be confused with the 'unit' of unital rings.


One can check that U is a functor from the category of rings, to the category of groups: a ring homomorphism must map units to units. It has a left adjoint, the integral group ring construction.


  Results from FactBites:
 
Uropathogenic Escherichia coli: Fimbriae and Motility Studies (2033 words)
The orientation of the invertible element that allows the expression of type 1 fimbriae is defined as "on," and the opposite orientation, in which no transcription occurs, is defined as "off." During the course of a UTI with strain CFT073, the fimbriated “on” orientation peaked at 24 h.
invertible element to switch orientations during infection is itself a virulence trait.
Mutants that rendered the invertible element incapable of switching orientations were used to assess the role of the invertible element in virulence during a 7-day experimental UTI.
Inverse element - Wikipedia, the free encyclopedia (428 words)
In mathematics, the idea of inverse element generalises the concepts of negation, in relation to addition, and reciprocal, in relation to multiplication.
If e is an identity element of (S, *) and a * b = e, then a is called a left inverse of b and b is called a right inverse of a.
A square matrix M with entries in a field K is invertible (in the set of all square matrices of the same size, under matrix multiplication) if and only if its determinant is different from zero.
  More results at FactBites »


 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments
Please enter the 5-letter protection code

Want to know more?
Search encyclopedia, statistics and forums:

 


Lesson Plans | Student Area | Student FAQ | Reviews | Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms.