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The Utilization of Case-Based Reasoning                239

                       among different tree levels will show the relative importance of these attributes in the
                       process of developing a solution to the new problem. This T tree represents the stored
                       simulation cases in the case-base and defined as

                             = {  ,} Where,
                          N is the set of nodes (attributes),
                          n is the number of node in the tree
                          E is the set of edges connecting nodes and correlating attributes,
                          l is the level of the node, where
                          l = 0 Root node, l = 1 Category of the case, l = 2 Path number,
                          l = 3 # Doctors, l = 4 # Nurses, l = 5 # Lab technicians, l = 6 # Staff, and l = 7
                          Case Number
                          For each node in N, degree = number of directly connected nodes in levels l – 1 and
                        l + 1

                                 Table 3. The similarity (distance) matrix between different paths

                                                  Similarity (distance) matrix
                                                  Path 1    Path 2    Path 3    Path 4

                                     Path 1          0        10       20         10
                                     Path 2                   0        10         20
                                     Path 3                             0         10
                                     Path 4                                       0

                          The decision tree included three types of nodes:

                          (a)  A  root  node  acting  as  a  pointer  that  reference  all  sub-nodes  in  the  first  level
                              (starting node of the tree)
                          (b)  Intermediate nodes: all nodes in the tree with level 1 < l < 7. These nodes contain
                              the set of all child nodes Cl in the direct lower level that connected by edges.
                          (c)  Leaf  nodes:  all  nodes  in  the  tree  with  degree  =  l,  and  l  =  7.  Each  leaf  node
                              expresses  a  specific  set  of  attributes  relating  to  its  parents.  The  tree  of  the
                              developed case-base is shown in Figure 4.

                          For  the  stored  simulation  cases,  let  each  case  Ax  describe  as  a  set  of  different
                       attributes composing a distinctive case {a1, a2, al-1}. Also, for each attribute ai there is a
                       set Vi that contains all possible values of this attribute {vi1, vi2, … vir}. For example, the
                       first  attribute  a1  corresponding  to  the  category  of  the  simulation  problem  has  V1  =
                       {Optimization, Crowding, New design/methodology}.
                          The  induction  tree  approach  will  be  ready  to  use  as  soon  as  the  decision  tree  is
                       developed. Attributes of each of the new cases will compose a new set G = {g1, g2, … gl-
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