This figure shows two contours side by side, the one on the left is made up of three paths labelled capital gamma sub 1, capital gamma sub 2 and capital gamma sub 3. All have arrows marked in direction of travel. Capital gamma sub 1 is an arc travelling left to right top to bottom and looks like the lower left quarter of a circle. Capital gamma sub 2 is a vertical line travelling top to bottom and capital gamma sub 3 is an arc travelling right to left and top to bottom and looks like the top left quarter of a circle. The contour on the left is the reverse of this contour from capital gamma tilde sub 3 to capital gamma tilde sub 1.