The equation for the surface near a pinch point may be put in the form
where [4] denotes terms of degree 4 or more and is not a square in the ring of functions.
For example the surface near the point , meaning in coordinates vanishing at that point, has the form above. In fact, if and then {} is a system of coordinates vanishing at then is written in the canonical form.
The simplest example of a pinch point is the hypersurface defined by the equation called Whitney umbrella.
The pinch point (in this case the origin) is a limit of normal crossings singular points (the -axis in this case). These singular points are intimately related in the sense that in order to resolve the pinch point singularity one must blow-up the whole -axis and not only the pinch point.
A pinch-point is the level of inventories of a commodity or product below which consumers of that commodity or product become concerned about security of supply. When inventories are below the pinch-point, small changes in the balance of supply and demand can cause large changes in the price of the commodity or product.
The term was suggested in 1988 by Walter Curlook (Executive Vice-President of Inco Ltd) and was first published by Raymond Goldie with Rob Maiman in 1990. In 2000 Raymond Goldie trademarked the term.
References
↑ Raymond Goldie and Rob Maiman (1990). Pacific Rim 90 Congress of the Australasian Institute of Mining and Metallurgy.
↑ Raymond Goldie (2005). Inco Comes to Labrador. St. John's, Newfoundland, Canada: Flanker Press. p 61-62. ISBN 1-894463-75-7.
You can then secure cables as normal using Power-Tie or traditional zip ties, through the helpful slots on the Bridge face, providing an additional layer of cable protection at this key pinch point.
is not a square in the ring of functions.
near the point 
, meaning in coordinates vanishing at that point, has the form above. In fact, if 
and 
then {
} is a system of coordinates vanishing at 
is written in the canonical form.
called 