<P> To recover, this ambiguity is resolved by choosing E, because it occurs before F in the grammar . However, the resultant parser will not be able to recognize the valid input sequence bec, since the ambiguous sequence ec is reduced to (E → e) c, rather than the correct (F → e) c, but b E c is not in the grammar . </P> <P> The LALR (j) parsers are incomparable with LL (k) parsers: for any j and k both greater than 0, there are LALR (j) grammars that are not LL (k) grammars and conversely . In fact, it is undecidable whether a given LL (1) grammar is LALR (k) for any k> 0 (\ displaystyle k> 0). </P> <P> Depending on the presence of empty derivations, a LL (1) grammar can be equal to a SLR (1) or a LALR (1) grammar . If the LL (1) grammar has no empty derivations it is SLR (1) and if all symbols with empty derivations have non-empty derivations it is LALR (1). If symbols having only an empty derivation exist, the grammar may or may not be LALR (1). </P>

Right combination of parser for stream and view