# Thread: Boundary Complex of a Simplex

1. ## Boundary Complex of a Simplex

Just a quick question: what is the "boundary complex of a 3-simplex"? Is it just the complex consisting of the four 2-simplexes and their faces? I just want to be sure and I can't seem to find this defined anywhere. Thanks!

2. Originally Posted by Diamondlance
Just a quick question: what is the "boundary complex of a 3-simplex"? Is it just the complex consisting of the four 2-simplexes and their faces? I just want to be sure and I can't seem to find this defined anywhere. Thanks!
I think so. Because a $3$-simplex is a tetrahedron. And the boundary are the four triangles or $2$-simplexes.