if ongoal then [i],acce else
if (List.mem i acce) then accg,acce else accg,acce@[i]
| (_,_,_,Terms.Step (_,i1,i2,_,_,_)),_,_ ->
if ongoal then [i],acce else
if (List.mem i acce) then accg,acce else accg,acce@[i]
| (_,_,_,Terms.Step (_,i1,i2,_,_,_)),_,_ ->