Decomposition: is the process of breaking down in parts or elements.
High-level quantum algorithms are technology-independent, that is, allow arbitrary quantum gates, and do not take architectural constraints into account. Quite often, these algorithms involve quantum gates acting on n qubits. In order to execute such an algorithm in a quantum computer it is necessary to decompose these gates in an series of simpler gates.
The tweedledum library implements several decomposition algorithms. The following table lists all decomposition algorithms that are currently provided in tweedledum