Theorem 12.4.2

[mitchkeller]

https://activecalculus.org/vector/S_Vector_FTCLI.html#thm_PathIndepZero has a typo plus the theorem statement is wrong. The circulation needs to be zero along every closed curve in the domain for the vector field to be path-independent. (That's how the following activity is set up, so this is just needing to fix the theorem statement.)