Semester question

Question

What is handle ?

E->E+n|E*n|n

For n+n*n,write the handles in right sentential forms of the reduction.

Answer 1

Consider the following grammar:

E → E + n | E * n |  n

and a right-most derivation is as follows:

E → n + E  → n + E * n→ n + n * n

The n’s are subscripted for notational convenience.

Note that the reduction is in the opposite direction from n+ n* n back to E, where the handle at every step

Answer 2

during input scanning ..when we found the string which can directly reduced to production variable...such part is called as handle...

now look at you string n+n*n;...

now when we read n then there is possible reduction from n to E...so first handle is 'n'..

now we have replace it with E...so we get E+n*n...now we continue scan and we can see that E+n is another one that can be reduce to E...so our next handle is E+n......so replace E+n with E only ..

now we have E*n....this is also one more handle as it can be directly reduct to E....

SO ALL HANDLES WE GET IN SEQUENCE ARE 

n , E+n , E*n

Comments

I don't understand what is right sentential form?what does it mean?

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The right sentential form is the sentential form in which the input string when parsed from right-to-left and reduced whenever possible would give final output as the start symbol