Definition:Set Union/Historical Note

Historical Note on Set Union
The concept of set union, or logical addition, was stated by in his initial conception of symbolic logic.

The symbol $\cup$, informally known as cup, was first used by in Die Ausdehnungslehre from 1844. However, he was using it as a general operation symbol, not specialized for union.

It was who took this symbol and used it for union, in his 1888 work Calcolo geometrico secondo l'Ausdehnungslehre di H. Grassmann.

also created the large symbol $\bigcup$ for general union of more than two sets. This appeared in his Formulario Mathematico (5th edtion, 1908).