What is another word for direct sum?
Pronunciation: [da͡ɪɹˈɛkt sˈʌm] (IPA) 
Direct sum is a mathematical term that refers to the union of two subspaces. It is also known as the direct product, tensor product, or external sum. The direct sum of two subspaces is their sum which is not only linearly independent but also contains all possible linear combinations of the elements. Direct sums are widely used in linear algebra, topology, and abstract algebra as a means of combining different objects to form a new one. Some other synonyms for direct sum include disjoint union, Cartesian product, Kronecker product, and wedge product. Regardless of the term used, the concept of direct sum remains the same and is essential in many mathematical applications.
