Don't forget, "multiplicity" has its own negative connotations. http://www.imdb.com/title/tt0117108/
Shane Caldwell McGill University On Sun, Jan 18, 2015 at 12:26 PM, Edward A. Berry <ber...@upstate.edu> wrote: > Also RAID (REDUNDANT array of inexpensive disks). To me redundancy implies > robustness, overdetermination, like when I measure absorbance at 1500 > wavelengths to calculate the concentration of five absorbing species with a > 2-parameter baseline offset. > Exactly the connotation we want for our more-than-complete datasets. > eab > > On 01/18/2015 09:29 AM, Ian Tickle wrote: > >> PS see http://en.wikipedia.org/wiki/Cyclic_redundancy_check . >> >> I. >> >> On 18 January 2015 at 13:54, Ian Tickle <ianj...@gmail.com <mailto: >> ianj...@gmail.com>> wrote: >> >> >> At the risk of further extending this philosophical (if not >> etymological) discussion: in further defence of 'redundancy' I would point >> out that 'no longer needed' is not the only meaning of 'redundant', though >> admittedly it is the one that most often grabs the headlines! The meaning >> of 'redundant' in the context of employment is actually a relatively recent >> one and somewhat changed from the original meaning. >> >> In a scientific context there's a second meaning of 'redundant', and >> in fact this one is much closer to the original one. In information theory >> the term 'redundant' applies to extra information added to a message being >> passed down a transmission line, in order to reduce corruption and loss of >> information, i.e. redundancy is absolutely needed to reduce the error >> rate. In a crystallographic context the purpose of redundancy, i.e. >> measurements over and above those strictly required to obtain a structure, >> is also obviously to reduce errors. 'Additional' here clearly does not >> necessarily imply 'not needed'. >> >> 'Redundant' comes from the Latin 're', meaning 'again', and 'unda', >> meaning 'wave', from which of course we get 'inundated' and 'undulator', so >> 'redundant' means literally 'coming in waves' or 'overflowing'. So we >> could say that redundancy is the process of being inundated by data from an >> undulator! >> >> As BR points out 'multiplicity' has long been used to indicate the >> number of equivalent reflexions generated by the point-group symmetry (so >> in PG222 h00, hk0 and hkl have respectively multiplicites of 1, 2 and 4 for >> non-zero hkl). I googled 'reflection multiplicity' and the top hit was >> http://pd.chem.ucl.ac.uk/pdnn/symm2/multj.htm . >> >> Suppose I want to express the following idea: "Redundancy is likely >> to be correlated with multiplicity". How do I express that unambiguously >> if 'redundancy' is redefined as 'multiplicity'? >> >> Cheers >> >> -- Ian >> >> On 18 January 2015 at 13:12, Bernhard Rupp <b...@ruppweb.org <mailto: >> b...@ruppweb.org>> wrote: >> >> In defense of redundancy: >> >> While the IUCr online dictionary is notably silent about >> multiplicity, the term itself seems >> already oversubscribed and used differently in various >> crystallographic contexts. >> >> (i) Each general or special position in a crystal structure has >> a certain multiplicity, defined by symmetry. >> >> (ii) General reflection multiplicity M is usually is defined by >> reflection symmetry, and >> when reflections are affected by special operations, the >> resulting corresponding >> lower multiplicity because they map onto themselves is accounted >> for in the epsilon factor e. >> >> Btw a useful table of M and e is Iwasaki & Ito Acta Cryst. >> (1977). A33, 227-229 >> >> (iii) In case of Laue patterns, overlap of higher order >> reflections is also called Multiplicity afaik >> (various Helliwell/Moffat et al papers explain this). >> >> So expanding the term multiplicity to include multiple instances >> of measurements of the same reflections >> - while admittedly avoiding the connotation of obsolescence - >> adds to its promiscuous meaning, >> where context becomes part of the definition.... >> >> I abstain from making any suggestions because in the past this >> has led to interesting >> but time-consuming philosophical discourse, proving in general >> the multiplicity of my reflections >> and positions redundant if not obsolete. >> >> Best, BR >> >> -----Original Message----- >> From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK <mailto: >> CCP4BB@JISCMAIL.AC.UK>] On Behalf Of Kay Diederichs >> Sent: Sonntag, 18. Januar 2015 09:28 >> To: CCP4BB@JISCMAIL.AC.UK <mailto:CCP4BB@JISCMAIL.AC.UK> >> Subject: Re: [ccp4bb] Redundancy vs no of frames >> >> Dear Rohit Kumar, >> >> I prefer the term "multiplicity" instead of "redundancy" because >> the latter has a connotation of "not really needed any more". >> >> The relation then is >> >> multiplicity = c * number_of_frames * oscillation_range >> >> where the constant c depends mainly on the space group. >> >> HTH, >> >> Kay >> >> On Sun, 18 Jan 2015 02:35:46 +0530, rohit kumar < >> rohit...@gmail.com <mailto:rohit...@gmail.com>> wrote: >> >> >Dear all, >> > >> >Can anyone tell me how to calculate number of frames from >> redundancy or >> >vica versa >> > >> >Thank you >> > >> >> >> >>
