Roughly speaking, the function has minimum value in some neighbourhood
(interval) of each of the points A and C which are at the bottom of their respective
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valleys Similarly, the function has maximum value in some neighbourhood of points B
and D which are at the top of their respective hills For this reason, the points A and C
may be regarded as points of local minimum value (or relative minimum value) and
points B and D may be regarded as points of local maximum value (or relative maximum
value) for the function The local maximum value and local minimum value of the
function are referred to as local maxima and local minima, respectively, of the function