In formal language theory, the terminal yield (or fringe) of a tree is the sequence of leaves encountered in an ordered walk of the tree. In mathematics, logic and computer science, a formal language is a set of finite-length words (i. ... In computer science, a tree is a widely-used computer data structure that emulates a tree structure with a set of linked nodes. ...

Parse trees and/or derivation trees are encountered in the study of phrase structure grammars such as context-free grammars or linear grammars. The leaves of a derivation tree for a formal grammar G are the terminal symbols of that grammar, and the internal nodes the non-terminal or variable symbols. One can read off the corresponding terminal string by performing an ordered tree traversal and recording the terminal symbols in the order they are encountered. The resulting sequence of terminals is a string of the language L(G) generated by the grammar G. The Chomsky hierarchy is a containment hierarchy of classes of formal grammars that generate formal languages. ... In linguistics and computer science, a context-free grammar (CFG) is a formal grammar in which every production rule is of the form V → w where V is a non-terminal symbol and w is a string consisting of terminals and/or non-terminals. ... In computer science, tree traversal is the process of visiting each node in a tree data structure. ...