Explanation:
A function f has an absolute minimum at x = c if f(c) is the smallest function value on the entire domain of f, whereas f has a local minimum at c if f(c) is the smallest function value when x is near c.
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That pretty much covers it.
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The attached graph shows a function with a local minimum near x = -0.432 and an absolute minimum (which is also a local minimum) near x = 2.141.