# What does finitely additive mean?

## What does finitely additive mean?

In mathematics, an additive set function is a function mapping sets to numbers, with the property that its value on a union of two disjoint sets equals the sum of its values on these sets, namely, Therefore, an additive set function is also called a finitely-additive set function (the terms are equivalent).

Finitely additive measures are naturally defined on algebras (collections of sets which are closed under complementation and finite unions), but here they are considered on \sigma -algebras (closed under complementation and countable unions) because \mathcal L in Theorem 3.1 is a \sigma -algebra.

### What is meant by countably additive function?

noun Mathematics. a set function that upon operating on the union of a countable number of disjoint sets gives the same result as the sum of the functional values of each set.

uncountable collections of possibilities that individually have probability 0 but collectively have non-zero probability. Finite additivity without countable additivity allows even more distributions, like de Finetti’s countably infinite fair lottery.

#### What does it mean for a function to be additive?

In number theory, an additive function is an arithmetic function f(n) of the positive integer variable n such that whenever a and b are coprime, the function applied to the product ab is the sum of the values of the function applied to a and b: f(ab) = f(a) + f(b).

## Which property is countable additive?

The countable additivity axiom states that the probability of a union of a finite collection (or countably infinite collection) of disjoint events* is the sum of their individual probabilities.

### What is the example of additive?

They are added to food, for example, to enhance taste or color or to prevent spoilage. They are added to gasoline to reduce the emission of greenhouse gases, and to plastics to enhance molding capability.

What is the point of sigma-algebra?

Sigma algebra is necessary in order for us to be able to consider subsets of the real numbers of actual events. In other words, the sets need to be well defined, under the conditions of countable unions and countable intersections, for it to have probabilities assigned to it.

#### Which is an example of a sigma additive function?

One may define additive functions with values in any additive monoid(for example any groupor more commonly a vector space). For sigma-additivity, one needs in addition that the concept of limit of a sequencebe defined on that set. For example, spectral measuresare sigma-additive functions with values in a Banach algebra.