Parse open shop problems

Author: leonlan

read/Problem.py

@@ -9,6 +9,7 @@ class ProblemVariant(str, Enum):
     NW_PFSP = "NW-PFSP"
     HFSP = "HFSP"
     PMP = "PMP"
+    OSP = "OSP"
     # Permutation machine scheduling problems
     PFSP = "PFSP"
     SDST_PFSP = "SDST-PFSP"

read/machine.py

@@ -25,6 +25,7 @@ class MachineInstance:
     jobs: list[list[TaskData]]  # also defines precedence constraints
     permutation: list[tuple[int, int]] | None = None  # tuples of machine idcs
     no_wait: bool = False
+    open_shop: bool = False  # if True, job tasks have no precedence
     setup_times: list[list[list[int]]] | None = None
     objective: str = "makespan"
     due_dates: list[int] | None = None
@@ -64,6 +65,10 @@ def data(self) -> ProblemData:
                 for mach_idx, duration in task_data:
                     model.add_mode(task, machines[mach_idx], duration)
 
+            if self.open_shop:
+                # Open shop: a job's tasks have no precedence among them.
+                continue
+
             for pred, succ in pairwise(job2tasks[job_idx]):
                 # Assume linear routing of tasks as presented in the job data.
                 if self.no_wait:
@@ -197,6 +202,14 @@ def parse_npfsp(cls, loc: Path):
 
         return MachineInstance(num_machines, jobs)
 
+    @classmethod
+    def parse_osp(cls, loc: Path):
+        # Open shop has the same matrix format as NPFSP, but a job's tasks
+        # may be processed in any order, so there is no precedence between them.
+        instance = cls.parse_npfsp(loc)
+        instance.open_shop = True
+        return instance
+
     @classmethod
     def parse_nw_pfsp(cls, loc: Path):
         instance = cls.parse_npfsp(loc)

read/read.py

@@ -17,6 +17,7 @@ def read(loc: Path, problem: ProblemVariant) -> ProblemData:
         ProblemVariant.NPFSP: MachineInstance.parse_npfsp,
         ProblemVariant.NW_PFSP: MachineInstance.parse_nw_pfsp,
         ProblemVariant.PMP: MachineInstance.parse_pmp,
+        ProblemVariant.OSP: MachineInstance.parse_osp,
         # Permutation machine scheduling
         ProblemVariant.PFSP: MachineInstance.parse_pfsp,
         ProblemVariant.SDST_PFSP: MachineInstance.parse_sdst_pfsp,