P and NP Concepts · Algorithms · GATE CSE

Consider two decision problems $${Q_1},{Q_2}$$ such that $${Q_1}$$ reduces in polynomial time to $$3$$-$$SAT$$ and $$3$$-$$SAT$$ reduces in polynomial time to $${Q_2}.$$ Then which one of the following is consistent with the above statement?

Which of the following statements are TRUE?

1. The problem of determining whether there exists a cycle in an undirected graph is in P.

2. The problem of determining whether there exists a cycle in an undirected graph is in NP.

3. If a problem A is NP−Complete, there exists a non-deterministic polynomial time algorithm to solve A.

Let $${\pi _A}$$ be a problem that belongs to the class NP. Then which one of the following is TRUE?

Let S be an NP-complete problem and Q and R be two other problems not known to be in NP. Q is polynomial time reducible to S and S is polynomial-time reducible to R. Which one of the following statements is true?

The problems 3-SAT and 2-SAT are

Ram and Shyam have been asked to show that a certain problem Π is NP-complete. Ram shows a polynomial time reduction from the 3-SAT problem to Π, and Shyam shows a polynomial time reduction from Π to 3-SAT. Which of the following can be inferred from these reductions ?

Consider the decision problem 2CNFSAT defined as follows:

{ $$\Phi $$ | $$\Phi $$ is a satisfiable propositional formula in CNF with at most two literal per clause}

For example, $$\Phi = \left( {{x_1} \vee {x_2}} \right) \wedge \left( {{x_1} \vee {{\overline x }_3}} \right) \wedge \left( {{x_2} \vee {x_4}} \right)$$ is a Boolean formula and it is in 2CNFSAT.

The decision problem 2CNFSAT is

Suppose a polynomial time algorithm is discovered that correctly computes the largest clique in a given graph. In this scenario, which one of the following represents the correct Venn diagram of the complexity classes P, NP and NP Complete (NPC)?

The subset-sum problem is defined as follows:
Given a set S of n positive integers and a positive integer W, determine whether there is a subset of S Whose elements sum to W. An algorithm Q solves this problem in O(nW) time. Which of the following statements is false?

Let SHAM₃ be the problem of finding a Hamiltonian cycle in a graph G = (V, E) with |V| divisible by 3 and DHAM₃ be the problem of determining if a Hamiltonian cycle exists in such graphs. Which one of the following is true?

Consider three decision problems P₁, P₂ and P₃. It is known that P₁ is decidable and P₂ is undecidable. Which one of the following is TRUE?

Which of the following problems is not NP-hard?