Changes between Initial Version and Version 1 of Ticket #19184, comment 17


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Timestamp:
09/11/15 18:33:15 (5 years ago)
Author:
dimpase
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  • Ticket #19184, comment 17

    initial v1  
    66> I do not know half of this terminology that you use `^^;`
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    8 A 2-design is called symmetric if it has as many points as blocks, and with the number of blocks on a point equal the block size (e.g. PG(2,q), and, more generally, finite projective planes, are symmetric 2-designs).
     8A 2-design is called symmetric if it has as many points as blocks, and with the number of blocks on a point equals the block size (e.g. PG(2,q), and, more generally, finite projective planes, are symmetric 2-designs).
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    1010The dual of a symmetric 2-design is the design with points and blocks swapping the roles.
     
    1313A self-dual symmetric 2-design is called self-polar if it has a polarity.
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    15 OK, and for the good measure, a duality is an isomorphism between the design and its dual. Every polarity is a duality. Dualities can be computed in the same way as polarity (just drop order==2 requirement). So it would also be very natural to have `is_self_dual` method.
     15OK, and for the good measure, a duality is an isomorphism between the design and its dual. Every polarity is a duality. Dualities can be computed in the same way as polarity (just drop order==2 requirement). So it would also be very natural to have `is_self_dual` method, too.
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