Beispiel Grade2

Jan Burse, erstellt 22. Okt 2018
* Bonner's second counter factual example.
* Warranty & Liability
* To the extent permitted by applicable law and unless explicitly
* otherwise agreed upon, XLOG Technologies GmbH makes no warranties
* regarding the provided information. XLOG Technologies GmbH assumes
* no liability that any problems might be solved with the information
* provided by XLOG Technologies GmbH.
* Rights & License
* All industrial property rights regarding the information - copyright
* and patent rights in particular - are the sole property of XLOG
* Technologies GmbH. If the company was not the originator of some
* excerpts, XLOG Technologies GmbH has at least obtained the right to
* reproduce, change and translate the information.
* Reproduction is restricted to the whole unaltered document. Reproduction
* of the information is only allowed for non-commercial uses. Selling,
* giving away or letting of the execution of the library is prohibited.
* The library can be distributed as part of your applications and libraries
* for execution provided this comment remains unchanged.
* Restrictions
* Only to be distributed with programs that add significant and primary
* functionality to the library. Not to be distributed with additional
* software intended to replace any components of the library.
* Trademarks
* Jekejeke is a registered trademark of XLOG Technologies GmbH.
/* anna has already taken german, french and italian*/
:- multifile take/2.
take(anna, german).
take(anna, french).
take(anna, italian).
% /* anna would grade if she would not have taken italian */
% ?- retire(take(anna, italian)), grade(anna).
% Yes ;
% No
% /* anna would not grade if she would not have taken german */
% ?- retire(take2(anna, german)), grade(anna).
% No