SWI-Prolog -- (\=@=)/2

Documentation
- Reference manual
  - Built-in Predicates
    - Comparison and Unification of Terms
      - Special unification and comparison predicates
        
        unify_with_occurs_check/2
        
        =@=/2
        
        \=@=/2
        
        subsumes_term/2
        
        term_subsumer/3
        
        unifiable/3
        
        ?=/2
- Packages

Availability:built-in

+Term1 \=@= +Term2

Equivalent to ‘\+Term1 =@= Term2'. See =@=/2 for details.