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الكلية كلية العلوم للبنات
القسم قسم الحاسبات
المرحلة 2
أستاذ المادة محمد عبد الله ناصر الزبيدي
17/10/2012 09:15:11
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 ( N?? )*, whose elements are called production rules. Moreover, each production rule (?,? ) in P, denoted ?? ? , must have at least one nonterminal symbol in ? . In each such production rule, ? is said to be the left-hand side of the production rule, and ? 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?? }. By definition, the grammar has a single nonterminal symbol S , two terminal symbols a and b, and two production rules S ?aSb and S?? . 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 ? .
If N2 = {S}, ?2 = {a, b}, and P2 = {S ?aSb, S ??, 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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