TASK DEFINITION: Evaluate the similarity between them and classify them into classes from 0-5 as follows:
0 : The two sentences are completely dissimilar.
1 : The two sentences are not equivalent, but are on the same topic.
2 : The two sentences are not equivalent, but share some details.
3 : The two sentences are roughly equivalent, but some important information differs/missing.
4 : The two sentences are mostly equivalent, but some unimportant details differ.
5 : The two sentences are completely equivalent, as they mean the same thing.
PROBLEM: Sentence 1: Black train on train tracks. Sentence 2: A train on the train tracks.

SOLUTION: 4

PROBLEM: Sentence 1: elbaradei states that a middle east peace deal can only be reached in parallel with a security agreement based on eradicating all weapons of mass destruction from the region. Sentence 2: elbaradei was quoted as saying that a peace deal between israel and its arab neighbors must be reached in parallel with a security agreement based on eradicating all weapons of mass destruction from the region.

SOLUTION: 5

PROBLEM: Sentence 1: Higher than  per cent but not very high. Sentence 2: Lower than  per cent but not very low.

SOLUTION:
1