bam@csunb.csun.edu (brad williams) (03/19/91)
In article <13911@hacgate.UUCP> carmi@ipla01.hac.com (Aviram Carmi) writes: > >Hi, I recently came across some interesting problems and I would >appreciate any thoughts on them, or pointers to references. These interesting problems that he "came across" are from a takehome test I gave last week. Please, let him do his own test. I'll have a word with him in class tomorrow. )-: >1) We know that for PDA's (push down automata) we may define > acceptance by empty stack or by final-state and in either > case we will get exactly the CFL's (context free languages). > Is this true for DPDA's (deterministic PDA's)? > stack DPDA? > >2) For any PDA can we prove that the set of strings that can > appear on its stack is a regular set? > >3) We know that the concatenation of two DCFL is not nesseccrily > DCFL, but can the concatenation of two DCFL's that are not > regular end up being regular? > >Thanks, > >Avi >-- >Avi Carmi EMail: carmi@ipla01.hac.com Phone: (818) 702-3179
turpin@cs.utexas.edu (Russell Turpin) (03/19/91)
----- In article <13911@hacgate.UUCP> carmi@ipla01.hac.com (Aviram Carmi) writes: >> Hi, I recently came across some interesting problems and I would >> appreciate any thoughts on them, or pointers to references. In article <1991Mar18.214618.2310@csun.edu> bam@csunb.csun.edu (brad williams) writes: > These interesting problems that he "came across" are from a > takehome test I gave last week. Please, let him do his own > test. I'll have a word with him in class tomorrow. Since he was willing to plagiarize our work as his on a test, perhaps you should allow us to vote on the consequences of his cheating. In the academic tradition in which I was weaned, the standard punishment for plagiarism on a take-home test was a failing mark in the course. This seems appropriate, given both the importance of honesty to the academic endeavor, and also as a practical matter, to make sure that the expected benefit of such practice is small or negative. Russell