Changes between Initial Version and Version 1 of Ticket #19184, comment 17
 Timestamp:
 09/11/15 18:33:15 (5 years ago)
Legend:
 Unmodified
 Added
 Removed
 Modified

Ticket #19184, comment 17
initial v1 6 6 > I do not know half of this terminology that you use `^^;` 7 7 8 A 2design 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 2designs).8 A 2design 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 2designs). 9 9 10 10 The dual of a symmetric 2design is the design with points and blocks swapping the roles. … … 13 13 A selfdual symmetric 2design is called selfpolar if it has a polarity. 14 14 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 .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, too. 16 16 17 17