anchor.diff:  	;
   
   simple_arithmetic_expr
  -	: arithmetic_term
  -	| simple_arithmetic_expr ( '+' | '-' ) arithmetic_term;
  +	: arithmetic_term (( '+' | '-' ) simple_arithmetic_expr)?
  +	//| simple_arithmetic_expr ( '+' | '-' ) arithmetic_term
  +	;
   
   arithmetic_term
  -	: arithmetic_factor
  -	| arithmetic_term ( '*' | '/' ) arithmetic_factor;
  +	: arithmetic_factor (( '*' | '/' ) arithmetic_term)?
  +	//| arithmetic_term ( '*' | '/' ) arithmetic_factor
  +	;
   
   arithmetic_factor
   	: ( '+' | '-' )? arithmetic_primary;
  
positive.code: 	;
  
  entity_expr
  	: single_valued_association_path_expression
  	| simple_entity_expression;
  
  simple_entity_expression
  	: identification_variable
  	;
  
  functions_returning_numerics
  
negative.code: null_comparison_expr
  	: single_valued_path_expression 'IS' (keyNOT)? 'NULL';
  
  empty_collection_comp_expr
  	: collection_valued_path_expression 'IS' (keyNOT)? 'EMPTY';
  
  collection_member_expr
  	: entity_expr keyNOT? 'MEMBER' ('OF')? collection_valued_path_expression;
  
  comp_expr
  	: string_expr comparison_operator (string_expr)
  	| boolean_expr ('=' | '<>') (boolean_expr)
  	| datetime_expr comparison_operator (datetime_expr)
  