Brain Teaser: Solve This Math Word Puzzle

I came across this piece of puzzle today and then I decided to abandon my project and write a solution for it:

Each letter stands for a 1-digit number. No two letters may stand for the same number. Find a value for each letter from the following set: 0, 1, 4, 5, 6, 7, 8, 9.

'' ASK

+ GAVE

-------

' USED

The answer can be found here.

The concept is simple but the code is more verbose than what I thought... here is my python solution. Can anyone achieve one that is less verbose?

def permutation(num_list):

    if (len(num_list) == 1 or len(num_list) == 0):
         return [num_list];
     permutation_list = [];

    for i in range(len(num_list)):
         list_copy = num_list * 1 # deep copy
         item = list_copy.pop(i)
         one_less_perm_list = permutation(list_copy)
         for j in range(len(one_less_perm_list)):
              permutation_list.append([item]+ one_less_perm_list[j])
    return permutation_list


def solve_puzzle():

    combination = permutation([0, 1, 4, 5, 6, 7, 8, 9])
    var_list = ['A', 'S', 'K', 'G', 'V', 'E', 'D', 'U']

     for i in range(len(combination)):
          assignment = combination[i]
          set_of_answer = dict([(var_list[j], assignment[j]) for j in      range(len(var_list))])
          if set_of_answer['G'] + 1 != set_of_answer['U']:
               continue
          if (set_of_answer['A']*2)%10 != set_of_answer['S'] and      (set_of_answer['A']*2)%10 != set_of_answer['S']-1 :
               continue
          if set_of_answer['K']==0 or set_of_answer['E']==0:
               continue
          ret = set_of_answer['K'] + set_of_answer['E']
          if (ret%10 != set_of_answer['D']):
               continue
 
          carryover = ret/10
          ret = set_of_answer['S'] + set_of_answer['V'] + carryover
          if (ret%10 != set_of_answer['E']):
               continue
 
          carryover = ret/10
          ret = set_of_answer['A']*2 + carryover
          if (ret%10 != set_of_answer['S']):
              continue
         print set_of_answer

  print solve_puzzle()

But amazingly the PowerShell solution is so elegant! Too bad that it's not yet available to Vista and...wouldn't be open-sourced to Unix. Or else we can get ride of Bash or C-shell! Guess that this day won't come in near future...