在Prolog中測試軟件包衝突

Question

這是一個Prolog程序，我想檢查Linux軟件包之間的依賴關係以及是否存在任何衝突。

dep(gnome1,gcc7). 
confl(gcc7,gcc8). 

% recursive chain dependency 
depend(X,Y):- dep(X,Y). 
depend(X,Y):- dep(X,Z), depend(Z,Y). 

% conflict(X,Y) holds if X and Y depend 
on two packages which conflict, conflict between two 
packages should be a symmetric relation. 

% my poor attempt 
conflict(X,Y):- depend(X,A), depend(Y,B), (confl(A,B) | confl(B,A)). 

Answer 1

我認爲你的做法是差不多吧：

dep(gnome1,libc7). 
dep(gnome1,gcc7). 

dep(gnome2,gnome1). 
dep(gnome2,gcc8). 

confl(gcc7,gcc8). 

% recursive chain dependency 
depend(X,Y):- dep(X,Y). 
depend(X,Y):- dep(X,Z), depend(Z,Y). 

% conflict(X,Y) holds if X and Y depend 
% on two packages which conflict, conflict between two 
% packages should be a symmetric relation. 

conflict(X,Y) :- 
    depend(X,A), depend(Y,B), 
    X @< Y, % break symmetry 
    (confl(A,B) ; confl(B,A)). 

我平添了幾分（MIS）configuratoin的測試：

11 ?- conflict(X,Y). 
X = gnome1, 
Y = gnome2 ; 
false.