(* if one_dpm isn't already false at (r, h),
we want to check its behavior when updated with phi
bind_set (unit_set one_dpm) phi === phi one_dpm; do you remember why? *)
- let (truth_value, _, _) = one_dpm (r, h)
+ let (truth_value, r', h') = one_dpm (r, h)
in let truth_value' = truth_value && (truths (phi one_dpm) (r, h) = [])
(* new_dpm must return a (bool, r, h) *)
- in (truth_value', r, h)
+ in (truth_value', r', h')
in unit_set new_dpm;;
+ **Thanks to Simon Charlow** for catching a subtle error in previous versions of this function. Fixed 1 Dec.
+
* Representing \[[and φ ψ]] is simple:
let and_op (phi : clause) (psi : clause) : clause =
* Here are `or` and `if`:
+ (These probably still manifest the bug Simon spotted.)
+
let or_op (phi : clause) (psi : clause) =
fun one_dpm -> unit_set (
fun (r, h) ->
- in let truth_value' = (
+ let truth_value' = (
truths (phi one_dpm) (r, h) <> [] ||
truths (bind_set (negate_op phi one_dpm) psi) (r, h) <> []
) in (truth_value', r, h))
let if_op (phi : clause) (psi : clause) : clause =
fun one_dpm -> unit_set (
fun (r, h) ->
- in let truth_value' = List.for_all (fun one_dpm ->
+ let truth_value' = List.for_all (fun one_dpm ->
let (truth_value, _, _) = one_dpm (r, h)
in truth_value = false || truths (psi one_dpm) (r, h) <> []
) (phi one_dpm)