Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Area of the Medial Parallelogram of a Tetrahedron   When a pair of non-incident edges of a tetrahedron is chosen, the midpoints
of the remaining 4 edges are the vertices of a planar parallelogram. A formula
is given in terms of the six edge lengths for the area of this parallelogram.
It is not claimed that this formula is new, but it is certainly not well-known.
The author would be very grateful for a citation to an occurence of the formula
in previously existing literature (by e-mail to dyetter@math.ksu.edu).
  The result is of some current interest due to the work of Barbieri and
Barrett/Crane on attempts to formulate simplicial versions of quantum gravity.
  The new version corrects the coefficient in the main result. A paper of the
same title but with a vectorial version of the derivation of the area formula
was published by the author in the American Mathematical Monthly 106 (10)
December 1999 pp. 956-598.

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The categories of this paper are: q-fin
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-ex
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The categories of this paper are: comp-gas
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The categories of this paper are: cmp-lg
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-th
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The categories of this paper are: astro-ph
8
The categories of this paper are: hep-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: eess
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The categories of this paper are: quant-ph
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The categories of this paper are: funct-an
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The categories of this paper are: patt-sol
4
The categories of this paper are: cond-mat