Grammar-based Code
Grammar-based codes or grammar-based compression are Data compression, compression algorithms based on the idea of constructing a context-free grammar (CFG) for the string to be compressed. Examples include universal lossless data compression algorithms. To compress a data sequence x = x_1 \cdots x_n, a grammar-based code transforms x into a context-free grammar G. The problem of finding a smallest grammar for an input sequence (smallest grammar problem) is known to be NP-hard, so many grammar-transform algorithms are proposed from theoretical and practical viewpoints. Generally, the produced grammar G is further compressed by statistical encoders like arithmetic coding. Examples and characteristics The class of grammar-based codes is very broad. It includes block codes, the multilevel pattern matching (MPM) algorithm, variations of the incremental parsing LZ77 and LZ78, Lempel-Ziv code, and many other new universal lossless compression algorithms. Grammar-based codes are univers ...
[...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]