Proof of F-Theory being equivalent to a Toroidal Compactification of M-Theory

==Question==
Prove that F=MA_{\left(T^2\to0\right)} where "F" and "M" are F-Theory and M-Theory. 
 
How does one solve this? It doesn't make much sense to me. F-Theory is obviously a 12-dimensional theory, whereas M-Theory is 11-dimensional, and when compactified on a torus, 9-dimensional. So, how can a 12-dimensional theory be equal to a 9-dimensional theory? This doesn't make sense to me. 
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==Answers==
===Answer 1===
The keyword here is T-Duality. When M-Theory is compactified on a torus, that's like compactifying it on 2 circles. When you compactify M-Theory once on a circle, you get Type IIA String Theory. If you compactify it, again on a circle, by w:c:psiepsilon:T-Duality, this is Type IIB String Theory. 
By the definition of F-Theory, the conclusion follows trivially. 
 
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