acronyms possibly used in this test: CFG :acontext free grammar CFSM :acharacteristic finite state machine DFA :adeterministic finite automata

Transcription

1 EE573 Fll 2002, Exm open book, if question seems mbiguous, sk me to clrify the question. If my nswer doesn t stisfy you, plese stte your ssumptions. cronyms possibly used in this test: CFG :context free grmmr CFSM :chrcteristic finite stte mchine DFA :deterministic finite utomt FSM :finite stte mchine NDFA :non-deterministic finite utomt RE :regulr expression 0: Syllbus question. Cheting on n exm t Purdue is punishble by (circle ll tht re correct): A flogging B filure in the course C filure on the exm : Given the following digrm of one pss compiler, lbel the prts (phses) of the compiler nd its inputs nd outputs. Arrows represent I/O, dt flow, nd clls to routines/methods/functions. Allowed lbels re pgm source, prser, scnner, semntic routines. 2: Circle ll of the following tht cn be outputs from compiler. A Jv byte-codes B syntctic error messges C binry or executble file D ssembly lnguge 3: Circle the lest powerful of the following tht cn recognize regulr expression. A CFG B context sensitive grmmr C finite stte mchine

2 4: Circle ll of the following tht re recognizble by FSM. Note: [ i mens [ repeted i times. [ i ] j ;i;j 0 [ i ] j ;i <j;i 0 [ i ] j ;i = j; i 0 [ i ] j ;i >j;j > 0 [ 5 ] 4 [ 5 ] j ;j >0 5: DFA s cn recognize fewer regulr expressions thn NDFA s. TRUE FALSE 6: Given the NDFA: Strt stte is e λ 2 4 d 6 e 3 b 5 e 7 e the set of sttes fter converting to non-miniml DFA is: (where [i; j] denotes the stte formed from sttes i nd j in the originl NDFA.) A f[; 2; 3; 4]; [5; 6]; [7]g B f[; 2; 3; 4]; [3; 4]; [5]; [6]; [7]g C f[; 2]; [3; 4]; [5; 6]; [7]g D f[; 2]; [3; 4]; [5]; [6]; [7]g 2

3 7: Given the string now s is nd the trnsducer: Not(",,e,i,o,u, ) T(") T(") " T(,e,i,o,u, ) wht is the output from the trnsducer? A nws s B nwss C nw s Dnow ss 8: Circle ll tht re true of ScnGen: A DFA minimiztion is optionl B regulr expressions nd CFG s re input C output is scnner progrm D output is tble for driver progrm E escpes cn be used to hndle keywords 3

4 9: Wht RE is recognized by: b strt b b A Λ b Λ B + b + C b Λ jb Λ b D b + jb + b E bjbb 4

5 Use the grmmr G : S! A$ 2 A! BA 3 A! b 4 A! 5 B! cbd 6 B! 7 D! e 8 D! 9 D! (A) in questions 0 through 4, inclusive. The lnguge defined by this grmmr is L(G ). 0: Follow(A) is (circle the correct nswer): A fg B f$g C f$; )g D f)g : Follow(B) is: A fdg B fd; g C f; eg D f; e; (g E fe; (;b;$; )g 2: Predict(B), for production A! B is: A fc; b; $; )g B f$; )g C fc; b; g D f; cg 3: The following tble gives predict sets for G. Column Production gives the production, nd Predict gives the predict set for the production. Production Predict Production Predict S! A$ fb; c; $g A! BA fc; bg A! b fbg A! f$; )g B! cbd fcg B! nswer to question 2 D! e feg D! fb; $; );e;(g D! (A) f(g Circle ll tht re true bout G : A is LL() B is not LL() C my be LL() or not LL(), but cnnot tell from the Predict sets lone. 4: Add the productions B! C nd! to grmmr G to form grmmr G 0.IsL(G )=L(G 0 ) TRUE or FALSE? (Circle the correct nswer.) 5: Let G 2 be S! [B$ B! [B] B! Circle ll tht re true sttements: A G cn be recognized by DFA B G cn be recognized by n LL() prser C There exists grmmr G 0 such tht 2 L(G0 2 )=L(G 2), nd G 0 2 is LR(0). (Note, G = G 0 is possible.) 5

6 G 3 defined: Use the grmmr G 3, defined here, for questions 8 nd 9. S! X X! T X! P P! u P! vx T! id T! (X + X) 6: Circle the closure 0 (): A B C D E X!fflT X!fflP T!fflid T!ffl(X + X) X!fflT T!fflid T!ffl(X + X) X!fflT X!fflP X!fflT X!fflP T!fflid T!ffl(X + X) P!fflu P!fflvX 7: The CFSM for G 3 will hve stte [T! idffl]. Circle ll tht re true: A The ction for this stte is shift. B The ction for this stte is reduce. B The goto tble entry is empty. B The goto tble entry is non-empty. 6

7 Grmmr G 4 definition: Let G 4, used in problems 8, 9 nd 20 be: Production number Production S! B 2 B! Y 3 Y! id 4 Y! (B + B) with CFSM of 0 S --> B $ B --> Y Y --> id B S --> B $ 8 $ S --> X $ 5 9 ) id 6 ( Y Y --> id 7 B --> Y Y 2 B id B --> Y Y --> id 3 + B Y ) B --> Y Y --> id 4 ( id 8: Fill in the goto tble for sttes 0 nd 9. stte B Y id ( + ) $ : Fill in the ction tble for G 4. Actions should be R P, where P is production number (... 4), A for ccept, nd S for shift : This grmmr is LR(0). TRUE FALSE 7

8 A portion of n SLR() CFSM is shown below. Use this in nswering questions 2 nd 22. W 7 T --> id T --> id + id 8 T --> id + id T --> id * id Z T --> id * id 9 2: Wht symbol(s) should be on the trnsition lbeled W? Wht symbol(s) should be on the trnsition lbeled Z? 22: Fill in the ction tble entry for stte 7. Leve ERROR ctions blnk. Assume FOLLOW(T) = f)g. id + * )... 8

9 23: Given the grmmr: S! E$ E! (E) E! id nd the CFSM for the grmmr: ( 0 S --> E $ E --> id ( 3 E --> id E 5 E id ) S --> E $ 4 E --> id 6 $ 2 S --> E $ nd the string to be prsed (id), circle the correct sequence of stck sttes during the prse. st Stck Sttes 2nd Stck Sttes 3rd Stck Sttes 4th Stck Sttes ERROR ACCEPT 0 02ACCEPT 0 02ACCEPT 9