diff --git a/formula.py b/formula.py
index 19d512c..8f0fa0b 100644
--- a/formula.py
+++ b/formula.py
@@ -24,6 +24,8 @@ def undef_(self, other: int) -> None:
 
 
 class VarInfo:
+    __slots__ = ('n_', 'stat', 'rev')
+    undef: Set[int]
     rev: Dict[Clause, bool]  # role(+-) of its occurrences in each clause
     # number of negatively and/or positively occurrences
     stat: List[int]
@@ -35,108 +37,188 @@ def __init__(self, n: int):
         self.rev = {}
 
 
+class Asg_sideaff:
+    __slots__ = ('var', 'cl', 'value', 'role')
+    var: int
+    cl: Clause
+    value: bool
+    role: bool
+
+    def __init__(self, _var: int, _cl: Clause, _value: bool, _role: bool):
+        self.var = _var
+        self.cl = _cl
+        self.value = _value
+        self.role = _role
+
+
 class Formula:
+    __slots__ = ('raw', 'cnf', 'var', 'var_value', 'model', 'changes', 'frame', 'depth', 'one', 'zero', 'clacnt')
     # the following members are managed by push & pop, used in the recursive process
-    raw : List[List[int]]
+    raw: List[List[int]]
     cnf: Dict[int, Clause]
     var: List[VarInfo]
     var_value: Dict[int, Tuple[bool,  # value
-                                int,  # depth
-                                Optional[Set[int]] ] ]  # any edge table
+                               int,  # depth
+                               Optional[Set[int]]]]  # any edge table
     model: Optional[List[int]]
-    changes: List[Tuple[int, bool]]
+    changes: List[Union[int, Asg_sideaff]]
     frame: List[int]
     depth: int
+    clacnt : int
 
-    one: Set[Clause] # guaranteed to be size 0 after bcp exits
-    zero: Optional[List[int]] #not None during the inflating process(backjumping)
+    one: Set[Clause]  # guaranteed to be size 0 after bcp exits
+    zero: Optional[List[int]]  # not None during the inflating process(backjumping)
 
-    def get_var(self, x) -> VarInfo: return self.var[abs(x) - 1]
+    def get_var(self, x) -> VarInfo:
+        return self.var[abs(x) - 1]
 
     def assign(self, _var: int, value: bool,
                cause: Optional[Set[int]] = None) -> None:
         self.var_value[_var] = (value, self.depth,
                                 None if cause is None else copy(cause))
-        for cl, val in self.get_var(_var).rev.items():
-            x = cl.def_(_var * (-1 + 2 * val))
-            if val == value:
+        self.changes.append(_var)
+        for cl, role in self.get_var(_var).rev.items():
+            x = cl.def_(_var * (-1 + 2 * role))
+            if role == value:
                 self.before_unmount(cl)
                 del self.cnf[cl.i_]
             else:
                 if x == 0:
-                    self.one.remove(cl)
+                    self.one.discard(cl)
                     self.zero = list(cl.defined)
                 elif x == 1:
                     self.one.add(cl)
-        self.changes.append((_var, value))
-
-    def unassign(self, _var: int, value: bool) -> None:
-        for cl, val in self.get_var(_var).rev.items(): # FIXME rev是不可靠的，因为会新产生从句，导致rev变大
-            #TODO 新开一个list真的记一下这些修改，这是容易办到的事情
-            if val == value:
-                self.cnf[cl.i_] = cl
-                self.after_mounted(cl)
-            cl.undef_(_var * (-1 + 2 * val))
-        del self.var_value[_var]
+            self.changes.append(Asg_sideaff(_var, cl, value, role))
 
     def push(self) -> None:
         self.depth += 1
+        print('push called, depth = %d'% self.depth)
         self.frame.append(len(self.changes))
 
     def pop(self) -> None:
-        last = self.frame.pop() # throws IndexError indicating unsat
+        last = self.frame.pop()
         while len(self.changes) > last:
-            x, y = self.changes.pop()
-            self.unassign(x, y)
+            p = self.changes.pop()# FIXME really ? throws IndexError indicating unsat
+            if type(p) == Asg_sideaff:
+                if p.value == p.role:
+                    self.cnf[p.cl.i_] = p.cl
+                    self.after_mounted(p.cl)
+                p.cl.undef_(p.var * (-1 + 2 * p.role))
+            elif type(p) == int:
+                del self.var_value[p]
+            else:
+                assert False
         self.depth -= 1
+        print('pop called, depth = %d'% self.depth)
 
     def after_mounted(self, cl: Clause) -> None:
         for x in cl.undef:
             self.get_var(x).rev[cl] = x > 0
             self.get_var(x).stat[x > 0] += 1
-            assert self.get_var(x).stat[x > 0] <= 2 #TODO 这个数据调完删掉
+            assert self.get_var(x).stat[x > 0]
 
     def before_unmount(self, cl: Clause) -> None:
+
         for x in cl.undef:
             self.get_var(x).stat[x > 0] -= 1
             assert self.get_var(x).stat[x > 0] >= 0
             del self.get_var(x).rev[cl]
-
     def bcp(self) -> bool:
+        self.one = { i for k, i in self.cnf.items() if len(i.undef) == 1 }
         while (self.zero is not None) or len(self.one):
             if self.zero is not None:
-                self.one.clear()
+                print('bcp returned false!')
                 return False
             y = self.one.pop()
-            assert(len(y.undef) == 1)
+            assert (len(y.undef) == 1)
             m = next(iter(y.undef))
             self.assign(abs(m), m > 0, y.defined)
         return True
 
     def add_clause(self, cl) -> None:
-        i = len(self.cnf)
-        tp = self.cnf[i] = Clause(cl, i)
+        tp = self.cnf[self.clacnt] = Clause(cl, self.clacnt)
         self.after_mounted(tp)
-
+        self.clacnt += 1
 
     def __init__(self, n: int, cnf1: List[List[int]]):
         self.var = [VarInfo(1 + i) for i in range(n)]
         self.raw = cnf1
-        self.depth = 0
+        self.clacnt = self.depth = 0
         self.cnf = {}
         self.var_value = {}
-        self.model= None
+        self.model = None
         self.changes = []
-        self.frame  = []
+        self.frame = []
         self.one = set()
         self.zero = None
         for cl in cnf1: self.add_clause(cl)
 
     def validate(self) -> None:
         n = len(self.var)
-        self.model = { (i + 1) : False for i in range(n)}
+        self.model = {(i + 1): False for i in range(n)}
         for x, (y, p1, p2) in self.var_value.items():
             self.model[x] = y
         assert all([any([self.model[abs(j)] == (j > 0) for j in i]) for i in self.raw])
 
+    def inflate_cause(self, cause: Iterable[int]):
+        for i in cause:  # 找到低阶项或者同阶自由变量，特别的是同阶决定变量要yieldfrom 边表
+            i1 = abs(i)
+            val, dep, edg = self.var_value[i1]
+            if val: i1 = -i1
+            # if it's been an positive assignment before,
+            # now it's to be forced false, and vice versa
+            if dep < self.depth or edg is None:
+                yield (i1, edg is None)
+            else:
+                yield from self.inflate_cause(edg)
+
+    def decide(self) -> bool:  # True if already satisfied
+        assert not self.one and not self.zero
+        for q, cl in self.cnf.items():
+            if len(cl.undef) == 0:
+                assert False
+        dc = (0, 0, False)
+        for p in self.var:
+            if p.n_ not in self.var_value and (p.stat[0] + p.stat[1]):
+                if not p.stat[0]:  # pure
+                    self.assign(p.n_, True, None)
+                    return False
+                elif not p.stat[1]:
+                    self.assign(p.n_, False, None)
+                    return False
+                elif p.stat[0] > dc[0]:
+                    dc = (p.stat[0], p.n_, False)
+                elif p.stat[1] > dc[0]:
+                    dc = (p.stat[1], p.n_, True)
+        if dc[0] == 0:
+            assert len(self.cnf) == 0;
+            return True
+        x, y, w = dc
+        self.assign(y, w, None)
+        return False
+
+    def step(self) -> bool:  # throws IndexError
+        if self.bcp():
+            self.push()
+            if self.decide():  #FIXME 异常
+                return True
+            elif self.zero is None:
+                return False
+        assert self.zero
+        self.one.clear()
+        newlst: List[Tuple[int, bool]] = list(self.inflate_cause(self.zero))
+        self.zero = { x[0] for x in newlst }
+        if any(x[1] for x in newlst):
+            self.add_clause(self.zero)
+            self.zero = None
+        self.pop()
+        return False
+
+    def solve(self) -> bool:
+        try:
+            while not self.step(): pass
+            self.validate()
+            return True
+        except IndexError:
+            return False
 
diff --git a/main.py b/main.py
index 1e08df1..e0ff5ea 100644
--- a/main.py
+++ b/main.py
@@ -1,8 +1,7 @@
 from typing import *
 import sys
 import itertools as It
-from search import CdclEngine
-
+from formula import Formula
 
 def parse() -> Tuple[int, List]:
     tokens = iter([])
@@ -21,19 +20,12 @@ def parse() -> Tuple[int, List]:
         cc = []
         for num in map(int, tokens[4:]):
             if num == 0:
-                cc = list(set(cc))
                 if len(cc):
-                    cc.sort(key=abs)
-                    N = len(cc) - 1; i = 0
-                    while i < N:
-                        if abs(cc[i]) == abs(cc[i + 1]): break
-                        i += 1
-                    if i == N:
-                        clauses.append(cc)
+                    clauses.append(cc)
                     cc = []
             else: cc.append(num)
         if len(cc): clauses.append(cc)
-        assert(len(clauses) == m)
+        assert(len(clauses) == m) #FIXME
         return n, clauses
     except (ValueError, AssertionError) as e:
         print("invalid cnf format")
@@ -42,7 +34,7 @@ def parse() -> Tuple[int, List]:
 
 def main() -> None:
     n, M = parse()
-    fm = CdclEngine(n, M)
+    fm = Formula(n, M)
     if fm.solve():
         print('sat')
         for i in range(1, n + 1):
@@ -53,6 +45,6 @@ def main() -> None:
 
 
 if __name__ == "__main__":
-    sys.stdin = open('in.cnf', 'r')
+    sys.stdin = open('./testfiles/aim/aim-50-1_6-no-1.cnf', 'r')
     main()
 
diff --git a/search.py b/search.py
deleted file mode 100644
index 05e5eec..0000000
--- a/search.py
+++ /dev/null
@@ -1,63 +0,0 @@
-from typing import *
-from formula import Formula
-
-
-class CdclEngine(Formula):
-    def __init__(self, n: int, cnf1: List[List[int]]):
-        super().__init__(n, cnf1)
-
-    def inflate_cause(self, cause: Iterable[int]):
-        for i in cause: # 找到低阶项或者同阶自由变量，特别的是同阶决定变量要yieldfrom 边表
-            i1 = abs(i)
-            val, dep, edg = self.var_value[i1]
-            if val: i1 = -i1
-            # if it's been an positive assignment before,
-            # now it's to be forced false, and vice versa
-            if dep < self.depth or edg is None:
-                yield (i1, edg is None)
-            else: yield from self.inflate_cause(edg)
-    def decide(self) -> bool: #True if already satisfied
-        dc = (0, 0, False)
-        for p in self.var:
-            if p.n_ not in self.var_value and (p.stat[0] + p.stat[1]):
-                if not p.stat[0]: # pure
-                    self.assign(p.n_, True, None)
-                    return False
-                elif not p.stat[1]:
-                    self.assign(p.n_, False, None)
-                    return False
-                elif p.stat[0] > dc[0]:
-                    dc = (p.stat[0], p.n_, False)
-                elif p.stat[1] > dc[0]:
-                    dc = (p.stat[1], p.n_, True)
-        if dc[0] == 0:
-            assert len(self.cnf) == 0;
-            return True
-        x, y, w = dc
-        self.assign(y, w, None)
-        return False
-    def step(self) -> bool: #throws IndexError
-        if self.bcp():
-            self.push()
-            if self.decide(): return True
-            elif self.zero is None: return False
-        assert(self.zero)
-        newlst: List[Tuple[int, bool]] = list(self.inflate_cause(self.zero))
-        self.zero = [x[0] for x in newlst]
-        if any(x[1] for x in newlst):
-            self.add_clause(self.zero)
-            self.zero = None
-        self.pop()
-        return False
-
-    def solve(self) -> bool:
-        try:
-            while not self.step(): pass
-            self.validate()
-            return True
-        except IndexError:
-            return False
-
-    # 哪一步调push(), 哪一步pop()
-    # 向下走，push(), 向上走pop()，走向sibling: pop() & push()
-    #最开始做了0次假设，每push一次代表多做了一次假设