# What does this notation mean

by CornMuffin
Tags: notation
 P: 64 1. The problem statement, all variables and given/known data Here is the context: suppose $f=(f_1,...,f_{n+1})$ is a smooth retraction of $B^{n+1}$ onto $S^n$ But what does the following statement mean? $\int _{S^n}f_1df_2\wedge df_3 \wedge ... \wedge df_{n+1}$ 2. Relevant equations 3. The attempt at a solution