compiler-construction,programming-languages,computation-theory,memory-model,turing-complete

If by stack you mean the abstract data type which can only be accessed at the top, you're looking at pushdown automata. Deterministic PDAs can only handle deterministic context-free languages, non-deterministic PDAs all context-free languages, so they are not Turing complete. However, the "stack" in real computer architectures is not...

algorithm,turing-machines,np,np-hard,turing-complete

I) each NP problem can be solved in Exponential Time. Yes, this because it can be solved in polynomial time on Non Determinisitc Machine (definition of NP), and thus can be solved on a Deterministic Machine in exponential time. II) if P=NP then NP=NP-Complete. Yes, because if P=NP, "yes"...

turing-machines,turing-complete

The six basic operations/primitives that gives a language Turing completeness are: Right: Move the Machine’s head to the right of the current square Left: Move the Machine’s head to the left of the current square Print: Print a symbol on the current square Scan: Identify any symbols on the current...