Project Scope statement includes Acceptance Criteria : (As per 5.3.3.1 section of PMBOK 5, A set of conditions that is required to be met before deliverables are accepted). 

As per 5.5 section of PMBOK 5 -  Validate Scope is the process of formalizing acceptance of the completed project deliverables.   Project scope statement is not part of Inputs of Validate Scope.  

  Project Management plan contains only HOW acceptance can be obtained but not the criteria to accept.   Without Acceptance Criteria,  how the formlize approval can be obtained?