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The theory of error-correcting codes stems from Shannon's 1948 _A mathematical theory of communication_, and from Hamming's 1950 "Error detecting and error correcting codes".

9 votes

Best upper bound on rate for q-ary codes

So, the supposedly the sharpest one among all known bounds is somehow poorer than the bound you learn in Coding Theory 101 if the alphabet size $q$ approaches infinity. I think the reason you find it …
Yuichiro Fujiwara's user avatar
9 votes
Accepted

Bounded Hamming distance

I think you're assuming $x \not= y$ when you say "for any $x, y \in S$." In any case, your question seems like a mix of coding theory and design theory. If you find the case when $a = b = \frac{n}{2} …
Yuichiro Fujiwara's user avatar
7 votes
Accepted

"Codes" in which a group of words are pairwise different at a certain position

It is called perfect hash families in the design theory and computer science literature. A perfect hash family PHF$(N; k, v, t)$ is an $N \times k$ array on $v$ symbols with $v \geq t$, where for eve …
Yuichiro Fujiwara's user avatar
7 votes
Accepted

Codes with a twisted cyclic action

This is an extended comment that may be too long for the comment section. If I understand your question correctly, the linear codes you described are automatically trivial. Define $\pi_{c}$ to be th …
Yuichiro Fujiwara's user avatar
7 votes

Bounded Hamming distance

My previous answer is already too long, and this is too much to include in a comment. But I found a paper that studies the problem you asked here: R. M. Roth, G. Seroussi, Bounds for binary codes wit …
Yuichiro Fujiwara's user avatar
5 votes

Hot-topics in error correcting coding related to interesting math. ?

Edit: since I only implicitly answered your question in the title (i.e., hot topics in error coding codes related to interesting math), I think one of the current hottest ones is quantum error-correct …
5 votes

Cyclic Hamming Code

Before answering your question, not every Hamming code is equivalent to some cyclic code. For instance, the ternary $[4,2,3]_3$ Hamming code (aka the tetracode) is not equivalent to any cyclic code. …
Yuichiro Fujiwara's user avatar
4 votes

Probability of false decoding with LDPC codes

Generally speaking, understanding the decoding error probability of an LDPC code is a very difficult problem. Among major channels that have extensively been studied, as far as I know, binary erasure …
Yuichiro Fujiwara's user avatar
4 votes
Accepted

On MDS code property

I guess you exclude trivial MDS codes, generalized Reed-Solomon codes, and MDS codes that can be obtained by code extension. If you exclude them all, there are still a bunch of MDS codes. In general, …
Yuichiro Fujiwara's user avatar
3 votes

Good codes in practice for correcting combination of errors and erasures

Since you asked a reference, the early access pre-edit version of a paper that addresses exactly this problem you're considering just appeared in the IEEE Transactions on Information Theory: K. A. S. …
Yuichiro Fujiwara's user avatar
2 votes

Another formulation of error-correcting coding problem

Here's a long comment that can't be put in the comment section: If you know the location of errors in a binary system, and if errors are just bit flips, you can just flip those erroneous guys again. …
Yuichiro Fujiwara's user avatar
2 votes
Accepted

Partial backups

Your question is very similar to the extended idea of erasure-resilient codes discussed here: Y. M. Chee, C. J. Colbourn, A. C. H. Ling, Asymptotically optimal erasure-resilient codes for large disk …
Yuichiro Fujiwara's user avatar
1 vote

Block error-correcting codes over inhomogeneous alphabets

As mentioned in Hao Chen's answer, what you're looking for seems to be a good mixed code. There don't seem to be many papers on this. But apparently the following paper gives the best known general up …
Yuichiro Fujiwara's user avatar
1 vote

Techniques for showing optimality of given packing

My knowledge is limited when it comes to general combinatorial packings. But the kind of problem OP described is important in coding theory, where the difference between proving the existence of a goo …
Yuichiro Fujiwara's user avatar
1 vote

Doing column permutation under row overlap constraint

I doubt there is a particular algorithm worth mentioning for avoiding $2 \times 2$ all-one submatrices (or better known as $4$-cycles in the context of LDPC codes) in parity-check matrices which is sp …
Yuichiro Fujiwara's user avatar