TITLE: What is the amalg symbol?
QUESTION [6 upvotes]: I saw this formula: $A \amalg B$, where $A$ and $B$ are sets. I searched for the name of the symbol, "amalg", but haven't found a definition. What is the meaning of this symbol?

REPLY [3 votes]: I think the name "amalg" may come from the terminology free product with amalgamation, which occurs in algebraic topology, for instance in Van Kampen's theorem.