Tagged Questions

The study of data representations that enable error detection, error correction and/or compression.

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2
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1answer
16 views

Is the Source Coding Theorem straightforward for uniformly distributed random variables?

Shannon's source coding theorem states the following: $n$ i.i.d. random variables $X_1,\dots,X_n$ each with entropy H(x) can be compressed into more than n⋅H(x) bits with negligible risk of ...
0
votes
1answer
33 views

Hamming distance required for error detection and correction

I have already asked a pair of questions on the hamming distance, hamming code, valid and invalid codewords on this website, because I cannot understand those concepts fully, and in a few weeks or ...
2
votes
1answer
24 views

Typical set in Shannon's source coding theorem

I was following the textbook by David Mackay: Information theory inference and learning algorithms. I have question on asymptotic equiparition' principle: For an ensemble of $N$ $i.i.d$ random ...
2
votes
1answer
40 views

Source Coding Theorem: what happen when go below N⋅H(x) bits?

I was following the text book by David Mackay: information theory inference and learning algorithms, this could be found online on his website. I have question on the source coding theorem (emphasis ...
1
vote
1answer
43 views

Algorithm for designing a binary code with predefined distance

Suppose I have a matrix $A$ with its entry $A_{ij}$ denoting some kind of distance between class $i$ and $j$, is there a feasible algorithm for computing a binary coding for all the classes, such that ...
3
votes
1answer
57 views

Error-correction code for transmission only with bit-flipping from 0 to 1

I am using a transmission system that uses a Bloom filter (this part is out of my control). I want to send a small amount of data (32 bits) using this system. For each bit [0,31], I add its index to ...
0
votes
0answers
13 views

How to decode multiple-digit gamma codes and get the gap sequence? [duplicate]

How to decode gamma code ($\gamma$ code): 1110001110101011111101101111011 and get the gap sequence? Detailed information about Gamma codes ($\gamma$ codes) ...
2
votes
2answers
125 views

How to decode multiple-digit gamma codes and get the gap sequence?

How to decode gamma code ($\gamma$ code): 1110001110101011111101101111011 and get the gap sequence? Detailed information about Gamma codes ($\gamma$ codes) ...
3
votes
1answer
21 views

Lexicographical position of a string in its type class

I have the following problem: Given a string $x\in\{1,...,M\}^+$ of length $n$. Let $S$ be the set of all words with exactly the same numbers of occurences of smybols as in $x$. In fact, $S$ consists ...
5
votes
1answer
103 views

Are Lie theoretic codes impractical?

I have been recently studying Lie theory. I discovered that there is a family of Lie theoretic error correcting codes. I did not find any information except this paper: “Representations of Lie ...
2
votes
2answers
59 views

How to determine letter boundaries in Huffman encoded strings?

I'm trying to understand the Huffman compression algorithm. Lets assume the word : YESSSS According to Huffman tree we will get : S : 4 times -> Code : 0 Y : once -> Code : 01 E : once -> ...
7
votes
0answers
205 views

Huffman tree and maximum depth

Knowing the frequencies of each symbol, is it possible to determine the maximum height of the tree without applying the Huffman algorithm? Is there a formula that gives this tree height?
1
vote
1answer
63 views

Error detection/correction algorithm

We have 2 stations that communicate with each other, but we need to detect (or even correct) when something is wrong. We use 8 binary words: each consisting of 3 bits and to send it we code it as ...
4
votes
1answer
45 views

How many sequences in a prefix code can be compressed by m bits?

I have a little understanding problem with Appendix A ("Universal Codes") in the paper "Shannon Information and Kolmogorov complexity" by Gründwald and Vitanyi (Link). At the end of page 50, they ...
2
votes
1answer
117 views

Compute minimum hamming distance of a code

How do you find the minimum hamming distance of a code? A naive way is computing the distance of each pair of codewords in our code. It becomes hard when the code is sufficiently large. Is there a ...
-1
votes
1answer
70 views

Information of a stream of bits

Here is my problem. I have to compute the amount of information that is possible to encode in a string of bits. This string of bits represent a stream. Let us call such stream as ...
6
votes
2answers
88 views

Efficiently map different codes to rotation-different codes

Let $\mathbb{F}^n_2$ denote the set of $n$-bit 0-1 strings. How to construct an efficiently computable function $f:\mathbb{F}^n_2\to \mathbb{F}^m_2 (m>n)$ satisfying that $\forall u\neq ...
-1
votes
2answers
541 views

Network modem question

How would I solve the following can anyone help me.I know MIPS is basically how many instruction the processor can do per second but what should I do? Assume that we are receiving a message across a ...
4
votes
1answer
266 views

Algorithm for determining minimal set of covering prefixes

I have a set of strings. My goal is to find a minimal set of longest prefixes which will match most of that set. For instance, if my set is: ...
5
votes
1answer
96 views

Application of Expander Codes

I need to give a talk about expander codes at university (I'm a student of computer science). Since they have been introduced to show a family of codes looking good when thinking of the Shannon ...
5
votes
4answers
396 views

No compression algorithm can compress all input messages?

I just started reading a book called Introduction to Data Compression, by Guy E. Blelloch. On page one, he states: The truth is that if any one message is shortened by an algorithm, then some ...
5
votes
2answers
403 views

What is a good binary encoding for $\phi$-based balanced ternary arithmetic algorithms?

I've been looking for a way to represent the golden ratio ($\phi$) base more efficiently in binary. The standard binary golden ratio notation works but is horribly space inefficient. The Balanced ...
7
votes
1answer
123 views

Prove fingerprinting

Let $a \neq b$ be two integers from the interval $[1, 2^n].$ Let $p$ be a random prime with $ 1 \le p \le n^c.$ Prove that $$\text{Pr}_{p \in \mathsf{Primes}}\{a \equiv b \pmod{p}\} \le c ...
3
votes
1answer
485 views

Encoding the sequence 0110 and determining parity, data bit and value

I've been struggling with several Hamming code/error detection questions because the logic behind it doesn't seem to make sense. eg.1 eg.2 I don't really understand the above two examples and ...
8
votes
1answer
148 views

Error-correcting rate is misleading

In coding theory, 'how good a code is' means how many channel errors can be corrected, or better put, the maximal noise level that the code can deal with. In order to get better codes, the codes are ...