Revert "Fix bugs (#385)" (#386)

This reverts commit 69cd0ed8cda91c92dab6551a0c6dfd94d199cee7.

pina/solvers/pinns/basepinn.py

@@ -3,10 +3,12 @@
 from abc import ABCMeta, abstractmethod
 import torch
 from torch.nn.modules.loss import _Loss
+from ...condition import InputOutputPointsCondition
 from ...solvers.solver import SolverInterface
 from ...utils import check_consistency
 from ...loss.loss_interface import LossInterface
 from ...problem import InverseProblem
+from ...condition import DomainEquationCondition
 from ...optim import TorchOptimizer, TorchScheduler
 
 torch.pi = torch.acos(torch.zeros(1)).item() * 2  # which is 3.1415927410125732
@@ -24,7 +26,8 @@ class PINNInterface(SolverInterface, metaclass=ABCMeta):
     to the user to choose which problem the implemented solver inheriting from
     this class is suitable for.
     """
-
+    accepted_condition_types = [DomainEquationCondition.condition_type[0],
+                                InputOutputPointsCondition.condition_type[0]]
     def __init__(
             self,
             models,

pina/solvers/pinns/pinn.py

@@ -11,7 +11,7 @@ except ImportError:
 
 
 from .basepinn import PINNInterface
-from ...problem import InverseProblem
+from pina.problem import InverseProblem
 
 
 class PINN(PINNInterface):