Illuminance vs Luminance

It is sometimes worthwhile to understand how various metrics related to the measurement of light intensity work. Two of them are illuminance and luminance. They can sound really mundane and fool the subject into believing that both are actually the same thing. However, they are not. As a matter of fact, they are quite different.

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Figuring Out Functional Dependencies in Relations

A succinct definition of a functional dependency, such as X->Y, is that whenever X assumes a certain value (say x), and for that value of X (x), Y assumes a certain value y, then in every subsequent retrievals of X, whenever X assumes the value x, Y should assume the value y. Thats it! Functional dependency is no more than that. It is a very simple mathematical idea. It is the job of the subsequent normal forms to reduce the dependency of non-key attributes on non-key attributes.

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