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 L04 Morphology - Using Tries


     Morphology:  Towards Finite State Transducers


o  Trie data structure
                                
           l                            k                    
           |                            |                    
           a                            a                    
           |                            |                    
           D                            p                     
           |                            |                    
        --------                        a 
        |      |                        |
        a      A                        D
        |      |                        | 
        k    -------                    |
        |    |     |             ------------                   
        |    I     i             |     |    |                   
     -------       |             A     e    o                   
     |  |  |       A                        |                   
     |  |  |       |                        |                   
     A  e  o       M                        M                           
           |       
           M                               	


o  Abstracting out suffixes

     k            l
     |            |
     a            a
     |            |
     p            D
     |            |
     a         ---------
     |         |       |
     D(#1)     a       A
               |       |
               k (#1)  I

     #1:  Corresponds to paradigm for 'laDakA'

  
  -  Suffix trie (forward)

          #1
           |
        --------
        |      |
        e      o
               |
               M

  -  Alternatively use suffix trie backward


           Suffix Trie
 
                0
                |
            ---------
            |       |
          e (#1)    M
                    |
                 -------
                 |     |
                e(#1)  0(#1)

               
     #1:  Corresponds to paradigm for 'laDakA'


o  Finite state machines (alternative view of above disjointed trees)
   (Putting characters on edges rather than nodes.)

                  + 
                 / \
              l /   \ k
               +     +
             a |     | a
               |     |
               +     +
             D |     | p
               |     |
               +     +
             a |     | a
               |     |
               +     + 
             k |     | D
               |     |
               +     +
                \   / 
               0 \ / 0
                  +______
                e/ \o    \ A
                /   \     \
              (+)    +    (+)
                     |
                     |M
                    (+)
   Legend:
    - Nodes are shown using '+'
    - Accepting nodes are shown using '(+)'
    - Each arc is a directed arc from above to below
    - Empty string as arch label is shown using '0'

But the answer should tell us:
- Not just whether the input is a valid word,
- But its analysis:

+ Ex.: 'ladakoM' has root 'ladakA' with number plural, etc.

o For this we need finite state transducer.
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