③苇大 LL(1)文法 The first"L, means we scan the input from left to right; the second L means we create a leftmost derivation and the 1 means one input symbol of lookahead A grammar G is ll(1) iff whenever A->u v are two distinct productions of G, the following conditions hold for no terminal a do both u and v derive strings beginning with a (i. e. first sets are disjoint) at most one of u and v can derive the empty string if v=>*8 then u does not derive any string beginning with a terminal in Follow (A)LL（1）文法 The first “L” means we scan the input from left to right; the second “L” means we create a leftmost derivation; and the 1 means one input symbol of lookahead. A grammar G is LL(1) iff whenever A –> u | v are two distinct productions of G, the following conditions hold: - for no terminal a do both u and v derive strings beginning with a (i.e. first sets are disjoint) - at most one of u and v can derive the empty string - if v =>*  then u does not derive any string beginning with a terminal in Follow(A)