Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Reconstructing hv-Convex Polyominoes from Orthogonal Projections   Tomography is the area of reconstructing objects from projections. Here we
wish to reconstruct a set of cells in a two dimensional grid, given the number
of cells in every row and column. The set is required to be an hv-convex
polyomino, that is all its cells must be connected and the cells in every row
and column must be consecutive. A simple, polynomial algorithm for
reconstructing hv-convex polyominoes is provided, which is several orders of
magnitudes faster than the best previously known algorithm from Barcucci et al.
In addition, the problem of reconstructing a special class of centered
hv-convex polyominoes is addressed. (An object is centered if it contains a row
whose length equals the total width of the object). It is shown that in this
case the reconstruction problem can be solved in linear time.

3
The categories of this paper are: physics
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
21
The categories of this paper are: adap-org
28
The categories of this paper are: alg-geom
29
The categories of this paper are: funct-an
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
33
The categories of this paper are: plasm-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-th
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The categories of this paper are: q-fin
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The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
31
The categories of this paper are: ao-sci