Automata Theory Questions Medium
PSPACE and NPSPACE are complexity classes that deal with the amount of computational resources required to solve problems. The main difference between these two classes lies in the type of problems they represent and the computational resources needed to solve them.
PSPACE (Polynomial Space) is the class of decision problems that can be solved by a deterministic Turing machine using a polynomial amount of memory space. In other words, it represents problems that can be solved using a polynomial amount of memory, regardless of the time taken to solve them. PSPACE includes problems that can be solved in exponential time but with polynomial space.
On the other hand, NPSPACE (Non-deterministic Polynomial Space) is the class of decision problems that can be solved by a non-deterministic Turing machine using a polynomial amount of memory space. NPSPACE represents problems that can be solved in polynomial space, but the time complexity is not necessarily polynomial. It includes problems that can be solved in exponential time but with polynomial space.
In simpler terms, PSPACE focuses on the amount of memory space required to solve a problem, while NPSPACE considers both the memory space and the time taken to solve the problem. PSPACE is a subset of NPSPACE since any problem that can be solved in polynomial space can also be solved in non-deterministic polynomial space.
In summary, the main difference between PSPACE and NPSPACE complexity classes is that PSPACE deals with problems solvable in polynomial space, while NPSPACE considers problems solvable in non-deterministic polynomial space, taking into account both space and time complexity.