Variable-length code

In coding theory variable-length code is a code a variable numb

Vable-length codes can allow sources to be compressed and decompressed with zero error (lossless data compression) and still be read back symbol by symbol. With the right coding strategy an independent and identically-distributed source may be compressed almost arbitrarily close to its entropy. This is in contrast to fixed length coding methods, for which data compression is only possible for large blocks of data, and any compression beyond the logarithm of the total number of possibilities comes with a finite (though perhaps arbitrarily small) probability of failure.

Some strategies are Huffman coding, Lempel–Ziv coding and arithme.

Coheir extensions

The original code.

Using terms from formal language theory, follows: Let $S$ and $T$ and target alphabets, a totalmapping each symbol from $S$ to a sequence of symbols over $T$ , and the extension of $C$ to a homomorphism of $S^{*}$ into $T^{*}$ , which naturally maps each sequence of source symbols to a sequence of target symbols, is referred to as its extension.

Classes variable-length codes

Variable-length always no

Non-singular codes

A non-singular is injective.

For mapping $M_{1}=\{\,a\mapsto 0,b\mapsto 0,c\mapsto 1\,\}$ is not . Such singular coding may still be useful when some loss of information is acceptable (for example when such code is used in audio or video compression, where a lossy coding becomes equivalent to source quantization).
However, mapping $M_{2}=\{\,a\mapsto 1,b\mapsto 011,c\mapsto 01110,d\mapsto 1110,e\mapsto 10011,f\mapsto 0\}$ is

Uniquely decodable codes

A uniquely decodable with the Sardinas–Patterson algorithm.

The mapping $M_{3}=\{\,a\mapsto 0,b\mapsto 01,c\mapsto 011\,\}$ follow-set the map, new code).
Consider code $M_{2}$ in,^[1] is not 011101110011 codewords 01110–1110 011, 011 – 10011. cdb babe. syntax) that determine if source elements of this extension are acceptable. Such restrictions permit the decoding of the original message by checking which of the possible source symbols mapped to the same symbol are valid under those restrictions.