What does this notation mean

CornMuffin

1. The problem statement, all variables and given/known data

Here is the context:
suppose [itex]f=(f_1,...,f_{n+1})[/itex] is a smooth retraction of [itex]B^{n+1}[/itex] onto [itex]S^n[/itex]


But what does the following statement mean?
[itex]\int _{S^n}f_1df_2\wedge df_3 \wedge ... \wedge df_{n+1}[/itex]



2. Relevant equations



3. The attempt at a solution

xaos

this looks like it is being used in context of stokes theorem. any more information i think would be doing the problem. i think you can use the most obvious retract for this.