1 Answers
Option 3 : I and IV only
Concept:
If a problem A is polynomial time reducible to problem B. So, B is at least as hard as A.
Explanation:
Here, L1 is polynomial time reducible to L2, L2 is at least as hard as L1.
L3 is polynomial time reducible to L2
L2 is polynomial time reducible to L4.
Option 1:
if L4 ∈ P, then L2 ∈ P
L2 is polynomial time reducible to L4. L4 belongs to P type problem then L2 is also P type problem. So, it is true.
Option 2:
if L1 ∈ P or L3 ∈ P, then L2 ∈ P
If L1 belongs to P or L3 belongs to P, then L2 belongs to P. This is not true because L1, L3 is a polynomial time reducible to L2 not L2 is polynomial time reducible to L1.
Option 3:
L1 ∈ P, if and only if L3 ∈ P
L1 belongs to P, if and only if L3 belongs P. This is false because L3 is polynomial time reducible to L2 not L1.
Option 4:
if L4 ∈ P, then L1 ∈ P and L3 ∈ P
This statement is true because we know that L1 is polynomial time reducible to L2 and L3 is polynomial time reducible to L2 and L2 is polynomial reducible to L4 so L1 and L2 is polynomial time reducible to L4.