Problem Detail: Consider a deterministic Turing Machine $D$ which has an infinite tape in both directions. We don’t have exact information about it; what we know is that its alphabet is ${a, b, c}$ and there are at least three states Read More …
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[Solved]: Are compilers able to detect alternating accesses to arrays and interleave them in memory?
Problem Detail: Is it possible to design a compiler which optimizes a loop in which arrays are accessed in alternate fashion? For example like this: // int[] a,b int sum = 0; for(int i = 0; i < n; i++) { Read More …
[Solved]: Are two elements always in a relation within a partially ordered set?
Problem Detail: In a partially ordered set, am I always able to order two arbitrary elements out of the set? Or is it possible that two elements within the set have no order relation to each other? For example if there Read More …
[Solved]: How do you describe a language that is generated by Context Free Grammer
Problem Detail: I am familiar with describing Regular Expressions but when it comes to describing CFG I get confused. Do you describe it in words like you would regular expressions or do you do something like this ? this is the Read More …
[Solved]: Expressing semantics of an array as a function
Problem Detail: An assignment questions asks the following: Consider an array ‘var a : array[1..10] of real’. Express the semantics of this array as a function, defining the domain and codomain (you might also be able to write the rule). In Read More …
[Solved]: RDT2.1 – does the Sender listener to “ack” even though state=ready?
Problem Detail: Computer Networking: A Top Down Approach Featuring the Internet, Jim Kurose, Keith Ross Addison-Wesley 4nd edition , page -223. Also here slide 60 . RDT2.1 (Reliable data transfer) – Sender(s): state=ready; i=0; On rdt_send(d,m): if state=ready then { Read More …
[Solved]: Data structure for range-value-sum
Problem Detail: I have to be able to perform insert, delete, range-value-sum, and range-2-max-values with a data structure. Range-value-sum(xl,xr): with a range [xl,xr] (for a range query), it reports the sum of values of all elements whose keys are in the Read More …
[Solved]: Reducing context-free languages with polynomial-time reductions
Problem Detail: So, let’s say we have two languages $L$ (which is any context-free language) and $M$ which is the basic CFL ${0^n1^n: ngeq 0}$. Can $L le_p M$ ? Why or why not? How do polynomial time reductions even work Read More …
[Solved]: Why is least fixed point (lfp) important in program analysis
Problem Detail: I am trying to get a big picture on the importance of least fixed point (lfp) in program analysis. For instance abstract interpretation seems to use the existence of lfp. Many research papers on program analysis also focus heavily Read More …
[Solved]: Simplifying a nested sum
Problem Detail: I’m trying to analyze an algorithm of a function, I can express the function in term of summation, but I have no clues on how I could simplify this summation down to get the run-time in tern of big Read More …
