We show simple constant-round interactive proof systems for 
problems capturing the approximability, to within a factor of $\sqrt{n}$, 
of optimization problems in integer lattices; specifically, 
the closest vector problem (CVP), and the shortest vector problem (SVP).
These interactive proofs are for the ``coNP direction''; 
that is, ...
                	
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We prove that all of the following assertions are equivalent:
There is a many-one complete disjoint NP-pair; 
there is a strongly many-one complete disjoint NP-pair;
there is a Turing complete disjoint NP-pair such that all reductions 
are smart reductions;
there is a complete disjoint NP-pair for one-to-one, invertible ...
                	
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