Solve the B question..

Strill a, b) where the last two symbols in each string are a reversal of the first two sym- bol = first symbol and penultimate symbol : second symbol first symbol examination are represented with the letters [A, B, C, D, Fl. A string such is bols (ie.. last Is Student grades in an examination are as ABFCAD sudent AD indicates the grades obtained by a student in six different subjects. The grammar nerate only those strings that have at most three Ds and no Fs wing, first construct non-deterministic finite automata or deterministic finite ce versa. R For the followin on and then convert it to a regular grammar. ry strings with an odd number of Os and an even number of 1 s. ntroduces a concat- 19. Binar 20. Strings over the binary alphabet that do not contain the substring 010. 21. Binary strings in which every pair of adjacent Os appears before any pair of adjacent 1 s. 22. The set of all binary strings having a substring 100 before a substring 111 (both must be pres- sed in this chapr21. s ent). Show the derivation for the string w = 001 001 101 11. 23. A run in a string is a sub-string made up of a single symbol. For example, aabbbed has a run of as of length 2 and a run of bs of length 3. The grammar must derive all strings over the alphabet la, b, c, d with at least one run of as of length 2 and a run of cs of length 3, uages: e string 0111011 gth. FA). What is the 24. Strings over la, b) such that the length of the string is a multiple of 3 but not a multiple of 4. 25. Strings of the form ab'wb where the alphabet is (a, b) and w is any string over the same alphabet 00. C. Describe the language of the following grammar as concisely as possibl f 00010111