Tuesday, 15 January 2019

{Cusps}[15th August 1988]


[Redbook5:293][19880815:1628]{Cusps}[15th August 1988]

.1628

I have written* for information on Thom’s Catastrophe Theory** – something I heard of many years ago, but only by name, and meant to follow up (and should have), but work etc., I guess, intervened. All I know of it now is that in Thom’s theory catastrophes are a kind of (presumably, mathematical) fundamental form incarnate (presumably in nature); and that it has something to do with cusps. *** A Cusp turns out to mean, ‘technically, the intersection of two curves’.**** In mathematics,# however, it seems that ‘A simple cusp is a point on a curve where the curve crosses itself, and where the two branches of the curve share a common tangent, the branches being on opposite sides of the tangent. For example, y2 = x3.


The curve above has a simple cusp at the origin, where the x-axis is the common tangent.’#*


*(to E[ncylopedia] B[ritannica] [who operated a question-answering service for buyers of their Encyclopaedias])

**[See end of footnotes, below]

***(It became popular in Europe in Gothic architecture – frequently decorated with leaves, heads etc.) (cf [[Redbook5:145][19880609:2400 [sic]]{Art, Architecture and Politics}[9th June 1988],] 145
eg
[The ms sketch is very much smaller but cannot be further reduced here]
(Architecture)

****E[ncylopedia] B[ritannica] III,810.
In S[horter] O[xford] D[ictionary] it is also ‘apex’, ‘peak’.

#(I have given maths a rest recently (although I ‘wanted’ to go on) in order to spend time on Booklet [sic] &c)

#*(Collins Gem Basic Facts Mathematics)

**[
Originated by the French mathematician Rene Thom in the 1960s, catastrophe theory is a special branch of dynamical systems theory. It studies and classifies phenomena characterized by sudden shifts in behaviour arising from small changes in circumstances. Catastrophes are bifurcations between different equilibria, or fixed point attractors. Due to their restricted nature, catastrophes can be classified based on how many control parameters are being simultaneously varied. For example, if there are two controls, then one finds the most common type, called a "cusp" catastrophe. If, however, there are move than five controls, there is no classification. Catastrophe theory has been applied to a number of different phenomena, such as the stability of ships at sea and their capsizing, bridge collapse, and, with some less convincing success, the fight-or-flight behavior of animals and prison riots.

The diagram above is taken from the Web & is not in the ms.
]

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