what's dependenct or constituency involved in a sentence?
In linguistics, when it comes to sentence analysis, immediate constituent analysis or IC analysis may probably be the top one method come into our minds. This theory was first mentioned by Leonard Bloomfield. The process and result of IC-analysis can, however, vary greatly based upon whether one chooses the consituency relation of phrase structure grammars(=consittuency grammars) or the dependency relation of dependency grammars as the underlaying priciple that organizes constituents into hierachical structures.
Constituent(成分结构)：A given word plus all the words that word dominates. This definition is neutral with respect to the dependency vs contituency distinction. It allows one to compare the IC-analyses across the two types of structure. A consitiuent is always a complete tree or complete subtree of a tree, regardless of whether the tree at hand is a constituency or a dependency tree.
Consituent 是语法分析的一个基本术语，指一个语言单位，可大可下，大到分句，小到语素，还有单词、词组等都属于constituent范畴。
Constituency relation: The constituency relation derives from the subject-predicate division of Latin and Greek grammars that is based on term logic. Basic clause structure is understood in terms of a binary division of the clause into subject (noun phrase NP) and predicate (verb phrase VP). The binary division of the clause results in a one-to-one-or-more correspondence. For each element in a sentence, there are one or more nodes in the tree structure that one assumes for that sentence.
成分结构关系：一个句子能够分析成一系列成分结构， 如主语+谓语，名词短语+动词短语等。这种分出的单位又可进一步分析出各自的成分（例如名次短语可以分为限定词+名词），这种成分分析法可以不断运用直到不能再分出更小的成分为止。一种语法如果完全以这种方式分析句子，即对句子做层级结构分析，像这种有成分基础的语法就叫做成分结构语法。
Dependency relation:By the time of Gottklob Frege, a competing understanding of the logic of sentence had arisen. Frege rejected the binary division of the sentence and replaced it with an understanding of sentence logic in terms of predicates and their arguments. The dependency relation is a one-to-one correspondence for every element (word or morph) in a sentence, there is just one node in the syntactic structure.
依存关系：依存关对应的是依存语法， 认为动词是句中最重要的中心单位，且为名词短语所依附一种语言理论。这种语法在结构式的各成分之间建立各种类型的依存关系，用来解释各种语法关系。句法结构采用依存树表示，每棵树包含一个支配语和一组依附语，每个依附语与支配语有特定的关系。例如，一个小句中，动词被视为支配语，依附语是那些名词短语。他们属于动词的配价指派各种值（叫做动词的Valency “价”），例如blush(脸红)是一价动词，give是三价动词。再比如在“on the box”. 这种介词短语中，介词支配名词，名词又支配冠词。依存关系通常用弧线表示，弧线连接的是词（而不是结构成分）