Observe the VSPL defined below and identify which sequences are valid. <letter>

Question

Observe the VSPL defined below and identify which sequences are valid.

<letter>             ::= a | b | c | d | e

<LETTER>          ::= V | W | X | Y | Z

<number>        ::= 0 | 2 | 3 | 4 | 8

<letters>           ::= <letter> | <letter> <letters>

<LETTERS>        ::= <LETTER> | <LETTER> <LETTERS>

<numbers>       ::= <number> <number> | <number> <numbers>

<sequence>      ::= <letters> <LETTERS> <numbers> | <LETTERS> <letters> <numbers>

Which of the following are valid sequences? You must clearly identify for each of the following sequences, which are valid and which are invalid.

1) CSE220

2) aZ20

3) VWXa84

4) Zbad88

5) Ey542

6) dYaZeWkZ

7) XYZcde348

8) XYZabc22

9) abcXYZ123

10) edc135790V

Explanation / Answer

1) CSE220 : Invalid There is No Letter as "C" <LETTER>          ::= V | W | X | Y | Z

2) aZ20 : Its Valid

<sequence>      ::= <letters> <LETTERS> <numbers>

=> <sequence>      ::= a Z<numbers><numbers> = > aZ20

3) VWXa84. : Valid

<sequence>      ::= <LETTERS> <letters> <numbers>

=> <LETTER> <LETTERS><letters> <numbers>

=><LETTER><LETTER> <LETTERS><letters> <numbers><numbers>

= VWXa84.

4) Zbad88: Valid

<sequence>      ::= <LETTERS> <letters> <numbers>

=><LETTERS> <letters> <letters><numbers>

=><LETTERS> <letters><letters> <letters><numbers><numbers>

= Zbad88

5) Ey542 : Invalid : No such elemnet as E , <LETTER>          ::= V | W | X | Y | Z

6) dYaZeWkZ Invalid : No such elemnet as k , <letter>             ::= a | b | c | d | e

7) XYZcde348 : Valid

<sequence>      ::= <LETTERS> <letters> <numbers>

=><LETTER><LETTER> <LETTERS><letters> <letters><letters><numbers><numbers><numbers>

=>XYZcde348

8) XYZabc22 : Valid

= > <LETTER><LETTER> <LETTERS><letters> <numbers><numbers>

=>  <LETTER><LETTER> <LETTERS><letters><letters><letters> <numbers><numbers>

XYZabc22

9) abcXYZ123 : Valid

<sequence>      ::= <letters> <LETTERS> <numbers>

<letters><letters><letters><LETTER><LETTER> <LETTERS> <numbers><numbers> <numbers>

=>abcXYZ123

10) edc135790V : Invalid

No such order exists to generate this sequence : Number can come only after letters, so not possible

<sequence>      ::= <letters> <LETTERS> <numbers> | <LETTERS> <letters> <numbers>

Thanks, let me know if there is any concern.

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