Mathematical Sciences Classification System
51Exx - Finite geometry and special incidence structures
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                            51E05General block designs [See also 05B05]
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                            51E10Steiner systems
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                            51E12Generalized quadrangles, generalized polygons
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                            51E14Finite partial geometries (general), nets, partial spreads
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                            51E15Affine and projective planes
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                            51E20Combinatorial structures in finite projective spaces [See also 05Bxx]
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                            51E21Blocking sets, ovals, $k$-arcs
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                            51E22Linear codes and caps in Galois spaces [See also 94B05]
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                            51E23Spreads and packing problems
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                            51E24Buildings and the geometry of diagrams
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                            51E25Other finite nonlinear geometries
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                            51E26Other finite linear geometries
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                            51E30Other finite incidence structures [See also 05B30]
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                            51E99None of the above, but in this section