Yes, this is possible with most induction cooktops - you will have to look at each manufacturer's recommendations to find how much distance is required below the cooktop.

I have been debating between 2 at the moment (Bosch 800 and GE Monogram). I found it interesting that the Ge requires nearly 12" of clearance yet every manual states that an oven can easily go under the cooktop.

Hi, Wally. What do you mean by 'every manual'? Which manual?

Some induction cooktops allow ovens underneath and others don't. Induction cooktops state how much clearance is required underneath their tops. Clearance and oven allowance may be different animals. Both require a careful reading of the manuals.

GE monogram website has downloadable manuals. This is a separate site from their overall GE appliance website.
Also, every site selling the monogram has a new area indicating that ovens CAN be installed underneath.

I just ordered my Bosch 500, and do not require an oven, so for me it was moot point.

Almost every induction cooktop that can be mounted over an oven says in the manual that you can only pair it with the same manufacturer's oven. This isn't just a sales ploy. Some manufacturers allow their oven A but not their oven B. It depends not only on clearance, but on where the electronics are, where the fans are, etc. They have to fit together. Also, you don't want the heat from the works of the cooktop to fry the oven's control system.

In the GE case, it is likely that they designed the fit between the cooktop and oven such that there would be sufficient cooling volume, which is what the 12" is about. The European models expect drawers, rather than doors, under the cooktop, in which case one makes a narrow air channel behind the oven for the cooling air. This is what the fan blows around the underside of the cooktop.