private boolean parsedValidPreferencesLine(String _form) {
		
		boolean result = true;
		
		// don't even check if parses encountered error already
		if (encounteredError()) {
			
			result = false;
			
		}
		
		// check form is cnf
		if (!_form.equalsIgnoreCase("cnf")) {
			
			result = false;
			println("Error: invalid form in preferences file. Expected 'cnf' got: '" + _form + "'");
			
		}
		
		// check for valid variables amount
		if (mNumberOfVariables < 1) {
			
			result = false;
			println("Error: invalid number of variables in preferences file. Expected at least 1 got: " + mNumberOfVariables);
			
		}
		
		// check for valid clauses amount
		if (mNumberOfClauses < 2) {
			
			result = false;
			println("Error: invalid number of clauses in preferences file. Expected at least 2 got: " + mNumberOfClauses);
			
		}
		
		return result;
		
	}