In its Fifth Assessment Report, the Intergovernmental Panel on Climate Change, a group of 1,300 independent scientific experts from countries all over the world under the auspices of the United Nations, concluded there's a more than 95 percent probability that human activities over the past 50 years have warmed our planet.
Scalar multiplication of two vectors (to give the so-called dot product) is commutative (i.e., aÂ·b = bÂ·a), but vector multiplication (to give the cross product) is not (i.e., a Ã b = âb Ã a). The commutative law does not necessarily hold for multiplication of conditionally convergent series.
An example of a ring that is not commutative is the ring of n Ã n real square matrices with n â¥ 2. Finally, a field is a commutative ring in which one can divide by any nonzero element: an example is the field of real numbers.o give a ring homomorphism from a commutative ring R to a ring A with image contained in the center of A is the same as to give a structure of an algebra over R to A (in particular gives a structure of A-module).