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Lecture 16, Lecture 20 - Coggle Diagram

- - - - Can not modify a variable direcly, needs to call Set
      - You can´t import machines that declares the same variable
      - Imports may be applied iteratively to obtain the target decomposition
    - - Sees link is not transitive
      - When to use Sees ?
        
        Stateless models
        
        Contains no variables
        
        May contains SETS or constants
        
        Purely functional operations
        
        Can be seen from everywhere in the project
  - - - feature to ease the functional decomposition by avoiding too much levels
      - May be defined only in implementations and may be called by operations been global or local
- - - - Understanding the requirements, interviews
      - Formalizing(making choices) in the current model
      - AT some point: type check, PO examination
      - Good B Model
        
        Properties
        
        Are the main Porperties formalized?Traceability
        
        Are they provrd?
        
        Is the complexity introduced gradually?
        
        Modularity and maintenability
        
        Are the decomposed modules simple enough?
        
        What is the cost of a modification?
    - - Proof Life Cycle
        
        Automatic Proof
        
        70-85%
        
        Interactive proof
        
        16%
      - Good B Model
        
        High number of proof obligations, low automatic proof rate?
        
        Complex/overcomplicated proof obligations?