[Inquiry] Re: Theme One Program

[Jon Awbrey]

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TOP.  Expository Note 9

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3.1.  Lexical Cacti (cont.)

Example 4.  Lexical Level:  all apes are bold

Figure 7 shows the abstract lexical cactus
and two forms of lexical files for the
character stream "all apes are bold ".

all apes are bold

        o
        |
   o so-o o  o
   |  |/ /   | 
lo-o eo-o eo-o o
 |/   |/   |/ /  o
lo---po---ro-o   |
 |          / do-o o
 |        /    |/ /
 |      /     lo-o o
 |    /        |/ /
 |  /         oo-o o
 |/            |/ /
ao------------bo-o
 |              /
 |            /
 |          /
 |        /
 |      /
 |    /
 |  /
 |/
 @

( a ( l ( l
        , ( )
        )
    , p ( e ( s
            , ( )
            )
        , ( )
        )
    , r ( e
        , ( )
        )
    , ( )
    )
, b ( o ( l ( d
            , ( )
            )
        , ( )
        )
    , ( )
    )
, ( )
)

(4 a3 (3 l1 (1 l1
            ,1 (0 )0
            )0
      ,0 p1 (1 e1 (1 s1
                  ,1 (0 )0
                  )0
            ,0 (0 )0
            )0
      ,0 r1 (1 e1
            ,1 (0 )0
            )0
      ,0 (0 )0
      )0
,0 b1 (1 o1 (1 l1 (1 d1
                  ,1 (0 )0
                  )0
            ,0 (0 )0
            )0
      ,0 (0 )0
      )0
,0 (0 )0
)0

Figure 7.  Lexical Cactus:  all apes are bold

At this point, all that we need to take away from the above examples
of lexical cacti is the prefix-sharing pattern of the data structure,
which apart from the cactus rather than tree forms would probably be
called "radix coding".  If one has noticed the extra "spikes" at the
right hand extremes of the cactus lobes, it would not be misleading
to view these for now as a form of "parity checks", or a built-in
redundancy for controlling potential errors in coding the data.

Jon Awbrey

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