I find my self in a situation, where I need to program a service, that can determine if two object in a huge database are the same. For simplicity, let’s say it’s used cars, and I want to determine if they are the exact same, based on various attributes e.g. brand, model name, year, milage, price, color etc. The problem is, that some of the attributes are obversely more significant/critical/important than others e.g. brand/model name HAS to be the same, where as the seller might wrongly have typed in the milage a slight bit differently. Additionally some times information such as the color might even have been left out, an hence I must fall back to less “unique identifying” information such as for an example the engine size. Apart from the direct weight/importance of each attribute there is another dimension of complexity involved – the attributes’ importance vary with each other. So let’s say e.g. that the car I’m comparing against the rest is very old, then suddenly the importance of the milage it self increases since it’s way more likely to be unique among similar cars, than compared to a younger car. This is obviously due to the fact, that the dispersion of milage on older cars are much wider than the one on younger cars.