Polynomial Time Isomorphism Subgraphs

Due to the nature of this approach, subgraph isomorphism algorithms are time consuming isomorphism is a combinatorial problem belonging to the nondetermin-istic polynomial time complete (NP complete) class of problems, which are widely believed to be unsolvable. Several authors suggested improvements to reduce the... 

Ideally, what is required is an algorithm which tests for the subgraph isomorphism in polynomial time (i.e., the time taken is a direct function of the number of nodes, or its square or cube etc.). Unfortunately, no such algorithm is known, and it is strongly suspected by mathematicians that no such algorithm exists, though this has not been proven. 

The subgraph isomorphism problem is one of a class of mathematical problems known as NP-complete (another is the well-known travelling salesman problem) and it has been proved that if a polynomial-time algorithm exists for one of these, such algorithms must exist for all of them. But none of them yet has a polynomial time algorithm. 

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