Related papers: There are no projective surfaces in M_4

This paper has been withdrawn.

This paper was withdrawn by the author due to a fatal error.

This paper has been withdrawn by the authour.

This paper has been withdrawn by the author due to a crucial error in the definition of homomorphism.

This paper has been withdrawn by the authors due to a crucial error.

This paper has been temprally withdrawn by the author

This paper has been withdrawn.

The paper is withdrawn. The proof has an error and it requires a different approach.

This paper has been withdrawn by the authors due to a gap in the proof of the main result (in 5.3).

The paper has been withdrawn due to a crucial error in section 3.

This paper has been withdrawn by the author.

The paper has been withdrawn.

This paper has been withdrawn by the author due to some mistakes

This paper has been withdrawn by the author(s)

This paper has been withdrawn by the author due to an error.

This paper has been withdrawn by the author, due to a crucial error in the proof of Lemma 3.1.

This paper has been withdrawn by the author due to an error in the last paragraph of step 2 of the main proof, on page 6.

This paper has been withdrawn by the author(s) for revision.

The paper has benn withdrawn because the computation of the external virial contains an error which invalidate the main result.

This paper is being withdrawn because an error was discovered in lemma 4.3. Although the rest of the paper appears to be correct, this error invalidates the proof of theorem 3.1 and theorem 3.3.