Fix intersections

1 files changed, 13 insertions, 10 deletions

diff --git a/src/act4e_mcdp_solution/solver_dp.py b/src/act4e_mcdp_solution/solver_dp.py
index b4b0461..2798d47 100644
--- a/src/act4e_mcdp_solution/solver_dp.py
+++ b/src/act4e_mcdp_solution/solver_dp.py
@@ -710,9 +710,11 @@ class DPSolver(DPSolverInterface):
                 return us
 
             def intersect_pair(u1: UpperSet[RT], u2: UpperSet[RT]) -> UpperSet[RT]:
-                # always get the bigger of the two minimals
-                minimals: List[RT] = [m for m in u1.minimals if m in u2.minimals]
-                return UpperSet.from_points(poset, minimals)
+                def poset_max(m1: RT, m2: RT) -> RT:
+                    return m1 if poset.geq(m1, m2) else m2
+
+                minimals: List[RT] = starmap(poset_max, zip(u1.minimals, u2.minimals))
+                return UpperSet(minimals=list(minimals))
 
             return reduce(intersect_pair, us)
 
@@ -740,14 +742,13 @@ class DPSolver(DPSolverInterface):
         # Return antichain that is fixed point of phi
         def kleene_ascent(phi) -> List[R1]:
             # initialize with bottoms
-            chain: List[RT] = dp.dp.R.global_minima().minimals
-            prev_chain = None
+            chain: List[RT] = list(dp.dp.R.global_minima().minimals)
+            prev_chain = []
 
             # Ascent procedure
             while chain != prev_chain:
                 prev_chain = chain
                 chain = phi(chain)
-                # assert chain, "No chain!"
 
             # Take R1 out of RT
             first = lambda r: r[0]
@@ -772,8 +773,11 @@ class DPSolver(DPSolverInterface):
                 return ls
 
             def intersect_pair(l1: LowerSet[FT], l2: LowerSet[FT]) -> LowerSet[FT]:
-                maximals: List[FT] = [m for m in l1.maximals if m in l2.maximals]
-                return LowerSet.from_points(poset, maximals)
+                def poset_min(m1: FT, m2: FT) -> FT:
+                    return m1 if poset.leq(m1, m2) else m2
+
+                maximals: List[FT] = starmap(poset_min, zip(l1.maximals, l2.maximals))
+                return LowerSet(maximals=list(maximals))
 
             return reduce(intersect_pair, ls)
 
@@ -795,12 +799,11 @@ class DPSolver(DPSolverInterface):
 
         def kleene_ascent(phi) -> List[F1]:
             chain: List[FT] = dp.dp.F.global_minima().minimals
-            prev_chain = None
+            prev_chain = []
 
             while chain != prev_chain:
                 prev_chain = chain
                 chain = phi(chain)
-                # assert chain, "No chain!"
 
             first = lambda f: f[0]
             chain: List[F1] = list(map(first, chain))