Related papers: From time to causality

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This paper has been withdrawn at the request of one of the authors.

The paper has been withdrawn by the author due to a gap in Proof of Theorem 1.1.

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This paper has been withdrawn by the author because eq.(4) and those subsequent are incorrect.

This paper and abstract have been withdrawn.

This paper has been withdrawn by the author.

The paper has been withdrawn by authors. The issues studied in this paper were changed so much that we have published a new paper considering these issues. See hep-th/0406074

This paper has been withdrawn by the author, since some results of the paper have been already obtained in [J.~Lewandowski, Class. Quantum Grav. 9 (1992), no. 10, L147--L151.]

This paper has been retracted, for obvious reasons.

This paper has been withdrawn due to crucial errors.

This paper has been withdrawn by the authors because it has been merged with paper arXiv:0903.3501v1 [math.DG]

This paper has been withdrawn by the author due to new results to be added.

This paper has been withdrawn by the author.

This paper has been withdrawn by the author.

This paper has been withdrawn by the author, since the author does not have enough time to answer every questions on this result.

This paper has been withdrawn

This paper has been withdrawn by the author(s), due the final version in math.QA/0604564