The Gateway to Computer Science Excellence
First time here? Checkout the FAQ!
x
+23 votes
3.9k views

Consider the grammar shown below. 

$S \rightarrow C \ C$

$C \rightarrow c \ C \ | \ d$

This grammar is

  1. LL(1)
  2. SLR(1) but not LL(1)
  3. LALR(1) but not SLR(1)
  4. LR(I) but not LALR(1)
asked in Compiler Design by Veteran (59.6k points)
edited by | 3.9k views

2 Answers

+33 votes
Best answer

ans is A

$First(S)=First(C)=\{c,d\}$

there are no multiple in single row of parsing table hence grammar is LL1

note : if we have $A \rightarrow B/C$ for grammar to be LL(1) first(B) intersection First(C) should be null otherwise grammar is not LL1.If First(B) contains $\epsilon$ then Follow(A) intersection First(C) should be null. Using this we can say grammar is LL(1) or not without constructing parsing table.

An $\epsilon$ free LL(1) grammar is also SLR(1) and hence LALR(1) and LR(1) too.

answered by Boss (31.7k points)
edited by
0
@Sachin Mittal 1

I have a small doubt ::

Statement 1 : For every DCFL there exits a LR(0) or a LR(1) grammer.

Statement 2 : For every DCFL there exits a  LR(1) grammer.

Which is true??

According to me first one.But the discussion and other links, points that second one is true.

I am confused a bit.Can you provide some reference on this.
0

@Arjun sir:-

IS the following statement true?

 If a grammar is LL(1) and not containing ϵϵ, then it is SLR(1) and so LALR(1) and LR(1). 
 

0
yes it is!
0
why?
0
An ϵϵ free LL(1) grammar is also SLR(1) and hence LALR(1) and LR(1) too.

Is this true Arjun sir?
0

wikki says-

 A ε-free LL(1) grammar is also a SLR(1) grammar. A LL(1) grammar with symbols that have both empty and non-empty derivations is also a LALR(1) grammar. A LL(1) grammar with symbols that have only the empty derivation may or may not be LALR(1).[5]

0
So what is the confusing part ?
+1

yes every LL(1) grammar in not LALR(1).

0
Still what is wrong with the given statement?
0
Can we say a grammar is also SLR(k),LALR(K),LR(k) if it is a epsilon free LL(k) grammar?
+1 vote

Answer is A 

answered by (413 points)
Answer:

Related questions



Quick search syntax
tags tag:apple
author user:martin
title title:apple
content content:apple
exclude -tag:apple
force match +apple
views views:100
score score:10
answers answers:2
is accepted isaccepted:true
is closed isclosed:true

40,880 questions
47,536 answers
146,091 comments
62,300 users