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

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Why is Hamming Weight (in the CRC context) independent from the data?

I'm designing a communication protocol for 24 to 52 bits (typically 32 bits) data including the CRC-8 for error detection. I'm trying to select the best polynomial for this kind of application. In ...
4
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1answer
56 views

Number of words within Hamming distance $\delta$

This is a problem I'm having reading Arora & Barak's book, page 378-379. They define: For two words $x, y \in \{0, 1\}^m$, the fractional Hamming distance of $x$ and $y$ is equal to the ...
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1answer
47 views

Need help understanding textbook solution

I am studying for my final exam in coding-theory class, and as textbook provides poorly written solution to the exercise question, I decided to ask the question here, hoping for more clarification. ...
3
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1answer
120 views

Is there a generalization of Huffman Coding to Arithmetic coding

In trying to understand the relationships between Huffman Coding, Arithmetic Coding, and Range Coding, I began to think of the shortcomings of fuffman coding to be related to the problem of fractional ...
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1answer
153 views

coding theory- perfect codes

I'm new to stackoverflow so please bear with me. A tutorial question I got given was as follows: You are given that $C \subseteq D \subseteq F^n_q$ where $|C| < |D|$ and $C$ is a perfect code. ...
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50 views

Two dimensional parity check

Firstly, I would like to apologize if I misplaced this topic / i think the theory of coding is close to CS / I am little bit confused right now, in the school we were learning about Hamming's code, ...
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1answer
116 views

What is the algorithm for Shannon-Fano code? am I correct?

I am wondering what is the true algorithm for the Shannon-Fano code? The the result I am getting based on the Algorithm in Wikipedia page contradicts the supposed/expected length of the produced code. ...
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1answer
52 views

Communication Complexity and Prefix Codes [closed]

I need an advice. There is in section "V. CONCLUDING REMARKS" of the paper [1], a term that only the autho's paper use: "PREFIX CODING COMMUNICATION". I googled the expression and the only result ...
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2answers
109 views

Hamming code — identical parity bits for different errors

(7,4) Hamming Code (HC) detects all 2-bit errors and corrects all 1-bit errors. However, there can be 2-, 3- or 4-bit errors that come with the same parity bits as that of 1-bit errors. Eg.: Let ...
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1answer
108 views

use of Hamming Distance in Communication Networks

I am trying to put things in places on the use of Hamming Distance (HD) in error detection and correction in Computer Networks. I'm looking for correction/verification on the following: HD is a ...
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3answers
167 views

Binary code with constraint

Suppose I have an alphabet of n symbols. I can efficiently encode them with $\lceil \log_2n\rceil$-bits strings. For instance if n=8: A: 0 0 0 B: 0 0 1 C: 0 1 0 D: 0 1 1 E: 1 0 0 F: 1 0 1 G: 1 1 0 H: ...
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1answer
52 views

What does feedforward inversion mean in the context of convolution and catastrophic codes?

i'm reading the article of J. L. Massey and M. K. Sain, "Inverses of Linear Sequential Circuits" (Date of Publication - April 1968) (here) and i cannot understand - what is "feedforward inversion"? ...
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1answer
33 views

How is the Varshamov-Tenegolts code decoded?

For $0 \leq a \leq n$ the VT code $VT_a(n)$ consists of all tuples $(x_1,x_2,..,x_n) \in \{ 0,1\}^n$ such that $ \sum_{i=1}^{n} ix_i = a (mod (n+1))$ For example $VT_0(4) = \{ 0000,1001,0110,1111 \}$ ...
3
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1answer
65 views

About codes over $\mathbb{F}_2$

I was looking through these notes but I am not sure I can locate the answer to these questions of mine - it would be great if someone can just even point out what to look for! So any set of binary ...
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0answers
26 views

Looking for some lossless compression theory [duplicate]

I'll apologize in advance if anything in here is ineloquent. Suppose we have a pair of lossless compression (C) and decompression (...
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0answers
25 views

How many parity syndromes are there?

In RAID 6, there is a parity scheme that allows 2 concurrent disk failures. This requires 2 ‘syndromes’, one of which is simply XOR, as used for RAID 5's only parity. In trying to find out whether ...
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4answers
6k views

Is Morse Code binary, ternary or quinary?

I am reading the book: "Code: The Hidden Language of Computer Hardware and Software" and in Chapter 2 author says: Morse code is said to be a binary (literally meaning two by two) code because ...
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0answers
52 views

Do correlated inputs imply existence of efficient communication protocols?

Suppose that I have 2 parties Alice and Bob. Alice gets an input $X$ and Bob gets input $Y$ where $X, Y$ are $n$-bit strings. In the classic communication complexity world, computing a function such ...
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0answers
40 views

What is the theory foundation of the binary encoding of data digits into an EAN-13 barcode? [closed]

In the Wikipedia, there is explanation about EAN-13 and several table, which are called "Structure of EAN-13" and "Encoding of the digits", but I did not know what theory the contents of the two ...
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1answer
50 views

Hamming and BCH codes

Why are Hamming codes the best 1-error-correcting codes? I need references. I know that hamming codes are the best 1-error-correcting codes but I want to know why they are best?
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0answers
34 views

Name of a type of code similar to block codes

I've encountered a system where I need to construct a sort of quasi block code: We want to communicate a symbol $s$ from a finite-sized alphabet $\mathcal{S}$ using $N$ segments of information. ...
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23 views

Why are long block lengths commonly assumed/used in channel coding proofs?

As the title states, why are long block lengths commonly assumed or used in channel coding proofs?
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12k views

Is Morse code without spaces uniquely decipherable?

Are all Morse code strings uniquely decipherable? Without the spaces, ......-...-..---.-----.-..-..-.. could be Hello World ...
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1answer
54 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 ...
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1answer
324 views

Compute the Hamming code with odd parity for the memory word 1101 1001 0001 1011

This is the problem I have: Compute the Hamming code with odd parity for the memory word 1101 1001 0001 1011 (2 pts.). In your solution, mark the parity bits as in the following example, where ...
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1answer
6k 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 ...
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1answer
62 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
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1answer
64 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 ...
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1answer
51 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
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1answer
140 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 ...
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0answers
16 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) ...
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2answers
591 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) ...
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1answer
31 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 ...
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1answer
156 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 ...
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2answers
110 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 -> ...
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1answer
547 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?
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1answer
86 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 ...
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1answer
68 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 ...
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1answer
291 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 ...
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1answer
72 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
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2answers
107 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 ...
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2answers
958 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 ...
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1answer
405 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
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1answer
106 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
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4answers
847 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
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2answers
546 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 ...
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1answer
133 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 ...
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1answer
790 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 ...
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1answer
169 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 ...