Arbitrage opportunity: Can do some "correlation" analysis. If a DAX is equivalent to 3-4 points of the CAC 40, then if the target of the French index is 4700 (it is currently sitting at around 4470), we are 230 points below target. The DAX is currently around 10630, which a target of (11077 - 10630) = 447.
If we multiply the targets of the CAC 40 by 3 or 4, we have something between 230 x 3 = 690 points of the DAX or 230 x 4 = 920 points of the DAX.
The CAC has to be roughly twice as strong as the DAX so it has either to go up in a sharper fashion, or the DAX has to pull back more often etc.