begin %TEMPRECUR%
Travel(x,y,t) :- go(x,go_t1,y,t), go_t1=0. 
Travel(x,y,t) :- Travel(x,tl_y,tl_t), go(g_city1,g_t1,y,t), tl_y-g_city1=0, tl_t-g_t1=0. 
end %TEMPRECUR%