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الكلية كلية العلوم للبنات
القسم قسم الحاسبات
المرحلة 2
أستاذ المادة محمد عبد الله ناصر الزبيدي
11/12/2011 8:53:52 AM
Grammar
Each Type of grammar G is defined as a mathematical system consisting of a quadruple , where :
N is an alphabet, whose elements are called nonterminal symbols.
? is an alphabet disjoint from N, whose elements are called terminal symbols.
P is a relation of finite cardinality on ( NE? )*, whose elements are called production rules. Moreover, each production rule (a,b ) in P, denoted a® b , must have at least one nonterminal symbol in a . In each such production rule, a is said to be the left-hand side of the production rule, and b is said to be the right-hand side of the production rule.
S is a symbol in N called the start .
Example: is a grammar if N = {S},? = {a, b}, and P = {S® aSb, S®l }. By definition, the grammar has a single nonterminal symbol S , two terminal symbols a and b, and two production rules S ®aSb and S®l . Both production rules have a left-hand side that consists only of the nonterminal symbol S. The right-hand side of the first production rule is aSb, and the right-hand side of the second production rule is l .
If N2 = {S}, ?2 = {a, b}, and P2 = {S ®aSb, S ®l, ab ®S} then is not a grammar, because ab ®S does not satisfy the requirement that each production rule must contain at least one nonterminal symbol on the left-hand side.
Type of Grammars: or hierarchy of Grammar
The four classes are Type 0 summarized in the table below:
X is at least one nonterminal or more and zero terminal or more
Y is any string
X is at least one nonterminal or more and zero terminal or more
Y is any string with length at least the length of X
X is one nonterminal
Y is any string
X is nonterminal
Y®tN ,Y®Nt,Y®t where t is terminal and N is nonterminal
Example
SabN®Sab\ aaN
N®bb Type 0
Sab®aaSb Type 1
S®aSb\ab Type 2
S®aS\a\Sa Type 3
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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