A Note on Interactions of (Non-Commutative) Instantons Via AdS/CFT

We consider the interaction between instantons and anti-instantons infour-dimensional N=4 super-Yang-Mills theory at large N and large 't Hooftcoupling as described by D-instantons via AdS/CFT duality. We give an estimateof the strength of the interaction in various regimes. We discuss also the caseof Non-Commutative super Yang-Mills theory where the interaction betweeninstantons and anti-instantons can be used as a way to probe the localityproperties of the theory in the supergravity picture, without explicitreference to the definition of local operators.