Advanced Production Techniques

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• Talk about 2 additional mechanisms in the procedural system
  • procedural partial matching
  • dynamic pattern matching

Procedural partial matching

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• 选择production的时候，不一定会选择到条件完全符合的，其他的production也会有机会被选择
• :ppm
• Condition testing with procedural partial matching
• conditions must be true: 必须完美匹配的条件
  • test the buffer must contains a chunk
  • all queries
  • all inequality tests on slots (!=, < , >)
  • special conditions specified with eval or bind operators
• conditions must be true: 可以不必完美匹配的条件：
  • equality tests for the slots of the chunk in a buffer
  • eg. a = 1 , a=b
  • the mismatching values must be similar.
  • 只有那些相似的production才会被选择
    • 例如：buffer是 a=1, p1的条件是a=1.1, 则p1也有可能被选择
  • use set-similarities command
• Procedual Partial Matching VS. Declearitive Memory Partial Matching
  • in PPM, only considered when similarity value which is greater than the current maximum similarity difference ([~ :md])
  • by default, all chunks has similarity of [~ :md]. thus otherwise any chunk will be a match to any other in the PPM
  • this disallowing can control which items are allowed to be partial matched in productions.
  • default is -1.0 (max difference , min similarity)
• Conflict resolution with procedural partial matching
  • 

    • : desired value for slot j in production i

    • : the actual valuue in slot j in the chunk in the buffer

    • : global parameter

    • : noise
    • : set of slots that production i had a partially matched value
• productions that are not a perfect match receive a reduction in utility
• That adjusted utility is used only for purposes of conflict resolution
  • not for utility learning
  • not for production compilation
• Simple procedural partial matching model
  • tutorial/unit8/simple-ppm-model.lisp
  • The conflict set trace parameter
    • :cst
    • model debugging aid
    • similar to the activation trace paramter
    • print the matched productions with their utility

      (P MEDIUM
        =GOAL>
       VALUE  [MEDIUM, SMALL, -0.5]       ;// printed in the trace of conflict set indicating this production is a partial match
       VALUE SMALL                                 ;// binded value is the value in the buffer (not the one in the production)
       ==>
        !OUTPUT! SMALL
        -GOAL>
       )
      

  • Turning on ppm
  • The large production
    • no similarity set, thus will not be considered as a candidate of partial matching
  • Adding noise
    • :egs 1
    • 40% of the time production middium will be selected, but printed value is still SMALL
  • Building Sticks Task alternate model
    • The original Task is in Unit6
      • Original : sperate production for under strategy and over strategy
      • Alternate: only has a decide production for each strategy
        • tutorial/lisp/bst-ppm.lisp
        • tutorial/unit8/bst-ppm-model.lisp
        • (bst-ppm-experiment n)
    • Strategy choice

      (p decide-over
      =imaginal>
      isa               encoding
      goal-length       =d          ;比较goal和c的长度
      b-len             =d
      ==>
      )
      

      (p decide-under
      =imaginal>
      isa               encoding
      goal-length       =d          ;比较goal和b的长度，partial matching机制可以自动帮助我们调整utility
      c-len             =d
      ==>
      )
      

Dynamic Pattern Matching

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• Useful where
  • instruction or example following are involved
  • flexibility or context dependence are necessary
• Basic Operation
  • demo : /tutorial/unit8/simple-dynamic-model.lisp
• Arbitrary slots in conditions
  • the ability to test arbitrary slots in the conditions of a production.
  • 根据上下文，测试任意slot （之前都是只能测试写好在程序中的固定slot）
  • slot name can also be a variable and dynamiclly instantiated

     (p start
      =goal>
    context  =context     ;context slot保存需要测试的slot名
    =context =x           ; 测试的slot是一个变量
    

  • can be within or across buffer.
  • multiple times is OK
• Arbitrary slots in actions
  • A variable may be used to specify a slot in any
    • modification
    • modification request
    • request action of a production
  • if undefined slot is used, it may cause warning or error (depending on buffer)
• Extending chunks with new slots
  • add new slot names to chunk
  • in the trace, it shows :

  • EXTEND-BUFFER-CHUNK IMAGINAL

• Constraints on dynamic pattern matching
  • No Search
  • finding a slot based on its value (NP-hard problems)

     (p not-allowed
     =goal>
     isa goal
     =slot 1
    

  • One level of indirection

     (p also-not-allowed
     =goal>
     isa example
     first-slot =s1
     =s1        =next-slot
     =next-slot value         ;caused 2 unbounded level
     ==> )
    

    • such a mechanism appears to be realizable within the basal ganglia of the human brain as shown in previous research
• Example Models
  • Semantic Model
    • knowledge representation
      • is dangerous
    • unit1: attribute = dangerous , value = true
    • unit8: dangerous(slot name) true
    • it is almost always better for the model to retrieve something and then test that result than to rely on retrieval failure.
    • 第一次search之后自动在chunk加上父类的属性，比如 麻雀自动拥有鸟的属性，这样第二次search的时候就会变快（不需要在一遍历和向上搜索）
  • Paired-learning Model
  • 将固定在production当中的 slot名 （如 word ， number）变成变量 =slot
  • 这些变量将由dm中的instruction operator决定 (required =slot)
    • op1 required word
    • op2 required number
  • Dynamic matching and production compilation
    • complied productions can retain some of the dynamic components or replaced with statically matched values
  • Data fit
    • using dynamic matching did not influence the model performance