Basic Notions
- Entropy
- Differential entropy
- Graph entropy
- Conditional entropy
- Mutual infor
Entropy
Definitions
\[ H(X)=\log\frac{1}{p_X(X)}.\]
The base of the logarithm defines the unit of entropy. If the logarithm is to the base 2, the unit of entropy is the bit. If the if the logarithm is to the base \(e\), the unit of entropy is the nat.
Mutual Information
Definitions
Let \(X\) and \(Y\) be discrete random variables defined on finite alphabets \(\mathcal{X}\) \(\mathcal{Y}\), respectively, and with joint probability mass function \(p_{X,Y}\). The mutual information of \(X\) and \(Y\) is the random variable \(I(X,Y)\) defined by
\[ I(X,Y) = \log\frac{p_{X,Y}(X,Y)}{p_X(X)p_Y(Y)}.\]
As with entropy, the base of the logarithm defines the units of mutual information. If the if the logarithm is to the base \(e\), the unit of entropy is the nat.
Information Theory Knowledge Database
- Basic notions
- Source coding
- Channel coding
Online Committee Report, ITA 2013
Summary
The website had been running smoothly and consistently until February 5th, when it experienced significant slowdowns and errors (error 504). The problem has been fixed on February 8th, with the website running up again, but the fundamental cause of the problem has not been precisely identified yet. The developers have scheduled additional time to fix the issue next week, and the Online Committee will provide more information then.
The main topics covered in this report are the following.
Online Committee Report, ISIT 2012
Summary
The website has been running smoothly and consistently. The main topics covered in this report are the following.
- Development of and transition to alternatives to the old mailing lists
- Sub-websites for Schools of IT
- Analytics
Online Committee Report, ITA 2012
Summary
The website has been running smoothly and consistently. A new set of features were released to the website two weeks ago and we working with SixFeetUp to develop an alternative solution to mailing lists. As usual, some figures regarding website usage are provided in the Analytics section.
The two main topics of this report are
Online Committee Report, ITW 2011
Summary
The website has been running smoothly and consistently. We are currently reviewing a set of upgrades that will be pushed to the main website in the next two weeks. As usual, some figures regarding website usage are provided in the Analytics section.
The three main topics of this report are
Online Committee Report, ISIT 2011
Summary
The website has been running smoothly and consistently. We are seeing a stabilization of the number of visits and increased access to the news posted on the website. Detailed figures are provided in the Analytics section.