BEGIN:VCALENDAR
CALSCALE:GREGORIAN
PRODID:UWA Whatson 2002
X-WR-CALNAME;VALUE=TEXT:What's On At UWA
X-WR-TIMEZONE;VALUE=TEXT:Australia/Perth
VERSION:2.0
METHOD:PUBLISH
BEGIN:VTIMEZONE
TZID:/softwarestudio.org/Olson_20011030_5/Australia/Perth
X-LIC-LOCATION:Australia/Perth
BEGIN:STANDARD
TZOFFSETFROM:+0800
TZOFFSETTO:+0800
TZNAME:WST
DTSTART:19700101T000000
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
UID:P-20121130T005118Z-1235-26585@events.uwa.edu.au
DTSTART;TZID=/softwarestudio.org/Olson_20010626_2/Australia/Perth:20121204T130000
DTEND;TZID=/softwarestudio.org/Olson_20010626_2/Australia/Perth:20121204T134500
CLASS:PUBLIC
CREATED:20121130T005118Z
DESCRIPTION:Groups and Combinatorics Seminar\n\nNeil Gillespie (UWA)\n\nwi
ll speak on\n\nCompletely regular codes with large minimum distance\n\nand
\n\nDaniel Hawtin (UWA) will speak on\nElusive Codes in Hamming Graphs\n\n
at 1pm Tuesday 4th of December in MLR2\n\n\n\nAbstracts:\n\nCompletely reg
ular codes with large minimum distance:\nIn 1973 Delsarte introduced compl
etely regular codes as a generalisation of perfect codes. Not only are com
pletely regular codes of interest to coding theorists due to their nice re
gularity properties\, but they also characterise certain families of dista
nce regular graphs. Although no complete classification of these codes is
known\, there have been several attempts to classify various subfamilies.
For example\, Borges\, Rifa and Zinoviev classified all binary non-antipod
al completely regular codes. Similarly\, in joint work with Praeger\, we c
haracterised particular families of completely regular codes by their leng
th and minimum distance\, and additionally with Giudici\, we also classifi
ed a family of completely transitive codes\, which are necessarily complet
ely regular. In this work with Praeger\, and also with Giudici\, the class
ification given by Borges\, Rifa and Zinoviev was critical to the final re
sult. However\, recently Rifa and Zinoviev constructed an infinite family
of non-antipodal completely regular codes that does not appear in their cl
assification. This\, in particular\, led to a degree of uncertainty about
the results with Praeger and with Giudici. In this talk I demonstrate how
I overcame this uncertainty by classifying all binary completely regular c
odes of length m and minimum distance $ elta$ such that $ elta>m/2$.\n\nEl
usive Codes in Hamming Graphs:\n\nWe consider a code to be a subset of the
vertex set of a Hamming\ngraph. We examine elusive pairs\, code-group pai
rs where the code is not\ndetermined by knowledge of its set of neighbours
. We provide an\ninfinite family of elusive pairs\, where the group in que
stion acts transitively\non the set of neighbours of the code. In our exam
ples\, we find that the\nalphabet size always divides the length of the co
de\, and prove\nthat there is no elusive pair for the smallest set of para
meters for which this\nis not the case.\n\nSpeakers: Neil Gillespie and Da
niel Hawtin
DTSTAMP:20121130T005118Z
LAST-MODIFIED:20121202T234259Z
LOCATION:Maths Lecture Room 2
ORGANIZER;CN=Michael Giudici:MAILTO:giudici@maths.uwa.edu.au
SEQUENCE:2
SUMMARY:Groups and Combinatorics Seminars
URL:https://events.uwa.edu.au/event/20121130T005118Z-1235-26585@events.uwa.
edu.au/whatson/maths-stats
END:VEVENT
END:VCALENDAR