1. understood that symbol string and set operations.
L={A,B, … ,Z,a,b, … ,z}
D={0,1, … ,9}
Description meaning under represented:
LUD: All letters and numbers in the set
The LD : the set of all strings of symbols consisting of a letter followed by a number composed of
L4 : a 4 All-letter symbols set of strings
* L : the set of all strings of symbols of the alphabet
+ D : All of a symbol string or a set of a plurality of digits
L (LUD) * set of all strings beginning with the letter symbols, followed by the letter, digits
- Grammar G (Z): Z-> aZb | ab definition of what kind of language?
answer:
Because Z-> aZb
So Z-> aaZbb
Because Z-> ab
So Z-> aabb
And because Z-> aZb
So aaZbb-> aaabbb
And because Z-> ab
So aabb-> aaabbb
L ( G ) = {anbn Shu n> = 1}
Thus defining L ( G ) is defined by A n- B n-
3. Write grammar quaternion form materials 22 pages in Example 2.2 identifier (VN, NT, P, S).
There grammar G = (Vn of, V T , P, S)
Vn = {L ( identifier ) , D ( letters ) , H ( number )} , V T = {A, B, C, D, ~~~, Y, Z, 0,1,2, ~~~, 9}
P={
<L>-><D>
<L>-><L><D>
<L>-><L><H>
<D>->a
<D>->b
<D>->c
……
<D>->z
<H>->1
<H>->2
<H>->3
……
<H>->9
}
S=<L>
4. Write the following expressions leftmost derivation, rightmost derivation.
G (E):
E=> E + T | T
T=>T * F | F
F=>（E）| i
- i*i+i
- i+i*i
- i+(i+i)
Observe different leftmost and rightmost derivation process.
最左推导：
E -> E + T
-> T + T
-> F + T
-> i + T
-> i + T * F
-> i + F * F
-> i + i * F
-> i + i * i
最右推导：
E -> E + T
-> E + T * F
-> E + T * i
-> E + F * i
-> E + i * i
-> T + i * i
-> F + i * i
-> i + i * i