Public Shared Function Not(Of T)( _
   ByVal expr As Expression(Of Func(Of T,Boolean)) _
) As Expression(Of Func(Of T,Boolean))

Dim expr As Expression(Of Func(Of T,Boolean))
Dim value As Expression(Of Func(Of T,Boolean))
 
value = PredicateBuilder.Not(Of T)(expr)

public static Expression<Func<T,bool>> Not<T>( 
   Expression<Func<T,bool>> expr
)

public:
static Expression<Func<T^,bool>^>^ Notgeneric<typename T>
( 
   Expression<Func<T^,bool>^>^ expr
) 

public void NotQuery() {
  var mgr = new DomainModelEntityManager();
  Expression<Func<Customer, bool>> crit1 = c => c.Country.Equals("Mexico");
  var finalcrit = PredicateBuilder.Not(crit1);
  var results = mgr.Customers.Where(finalcrit).ToList();
}