$2$nemember the init function of Haskell? It can be defined in Haskell as:

init :: $[a][a]$

init

init $(x$:$xs)=x$ : init $xs$

Formulate the appropriate Prolog rule init $(x_s,Y_s)$ which is true if $Y_s$ is the initial part of Xs$.$ That is$,$ the query init $([1,2,3,4,5],[1,2,3,4]).$ would evaluate to true, or the query init $([1,2,3,4,5],Y_s).$ would give $Y_s=[1,2,3,4].$

Hint: this rule will be recursive, and will have a corresponding base case and recursive case, analogous to the base case and recursive case, respectively, of the above Haskell function $-$ the main difference being that the Prolog rule init $(x_s,Y{s}_s)$ is a predicate, not a function.