| M.SVar sv -> txt_svar sv
| M.RVar rv -> txt_rvar rv
| M.Relation (i, r, p, x, []) -> "relation " ^ txt_refpath i r p ^ txt_set x
| M.SVar sv -> txt_svar sv
| M.RVar rv -> txt_rvar rv
| M.Relation (i, r, p, x, []) -> "relation " ^ txt_refpath i r p ^ txt_set x