权限错误： - 动态用户：谓词修改静态过程谓词/ 2

Question

我在Prolog中有一些代码，在编译时我有以下错误：

 PERMISSION ERROR- dynamic user:examples/2: modifying static procedure examples/2

这是我的部分代码（用于测试的代码）：

/* This part is for creating a cache and storing solutions, I got it from false */

:- dynamic(examples/2).

reset :- 
  retractall(examples(_, _)). 

eq(A, B) :-
  subsumes_term(A, B),
  subsumes_term(B, A).

cached_call(Goal) :-
  \+ (examples(First,_), eq(First, Goal)),
  copy_term(Goal, First),
  catch(
    ( Goal, 
      assertz(examples(First, Goal)),
      fail  
    ),    
  Pat,  
  (reset, throw(Pat))).

  cached_call(Goal) :-
    examples(First, Results),
  eq(First, Goal),
  Results = Goal. 

 /* my function, just for testing the cached technology */
  myFunction(V1, V2, Result) :-
  cached_call(keepValue(V1, V2, V1cover, V2cover)),
  Result is V1/V1cover + V2/V2cover.  /* V1cover, V2cover are the value of the first called time of myFunction, they become constants for next called times of myFunction */ 

  myFunction(0,0,0).   

  keepValue(V1, V2, V1cover, V2cover) :-
    V1cover is V1, 
    V2cover is V2. 

当我编译这段代码时，我收到了错误。请告诉我为什么？非常感谢。