Q:

To break down a problem

There exists a problem or goal which cannot be achieved in one action, therefore one breaks the problem into smaller problems and solves each to ultimately reach the goal.
In one word, what verb is one doing to the problem?

A:

It is called problem decomposition or decomposing a problem. According to State Uni. Of New York

Problem decomposition is the problem solving strategy of breaking a problem up into a set of subproblems, solving each of the subproblems, and then composing a solution to the original problem from the solutions to the subproblems.

Definition of decompose according to Merriam Webster  is:

to separate into constituent parts or elements or into simpler compounds

