A Visual Interactive Tool For the Course

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A Visual Interactive ToolFor the Course
Automata and Formal Languages

• Holon Institute of Technology
• Mark Trakhtenbrot, Vladimir
  Nodelman, Avi Lamai
• The Open University of Israel
• Judith Gal-Ezer, Rina
  Zviel-Girshin, Michal Armoni,
• 
  Yahalom Humi

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The course

• Mandatory course for 2nd year CS students
• Studies mathematical models of computation
  (automata, grammars), their properties and
  expressive power, transformations, etc.
• Provides a strong background for a variety of CS
  areas construction of compilers, verification,
  design of digital systems, etc.

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Learning a theoretical CS course is difficult
Why?

• Heavy use of formal methods
• Intuition behind formal concepts is not always
  clear
• Serious challenge - formal math language
• to describe abstract objects, their properties
  and relations
• Needed ability of precise math reasoning

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Learning a theoretical CS course is difficult
Why?

• Students background and motivation
• significant break after the high school
• certain erosion in math skills required for CS
  studies
• seeking a high-tech career tend to view
  theoretical courses as something not needed for
  real work

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More problems

• Slow feedback
• Student becomes aware of certain
  misunderstandings only when getting back the
  checked assignment
• Often happens too late
• already busy with learning another material

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And more

• Communication problems
• difficulty to use formal language for asking
  questions
• often not supported technically
• leads to a verbal mess
• In distance education (OpenU)
• rare face-to-face classes

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As a result

• Concepts remain too abstract
• Theorems and algorithms are used improperly
• Common problems left without proper attention

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The challenge

• Help to
• make formal concepts more clear and tangible
• make communication about them easier
• discover problems earlier
• get answers in real time
•  
• Use technology to address these issues
•  

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To make this happen

• Developed
• interactive tool for visual hands-on
  exploration
• of the studied computational models
• Prototype
• - covers automata and grammars chapters of the
  course
• - Windows application, downloaded from the
  course site
• Internet version
• - so far, automata only

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Interactive tool for AFL course

• Supports the self-study process
• Build-in lessons
• - based on pre-defined scenarios
• Build-in exercises and exams
• - american and open questions
• - automatic check of solutions
• - tips provided in case of error
• Unlimited exercising

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Interactive tool for AFL course

• Major features
• Visual creation of computational models
• Static checks of model consistency and
  completeness
• Interactive simulation and animation
• Operations on automata and regular languages
• Transformations of models
• Traceability
• Different levels of details

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Visual creation of models

• Learn basic elements, their properties
  relationships
• Different views of model (diagrams vs. math
  notation)

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Static checks

• Reveal hidden properties find errors / omissions
• Examples no final states, missing transitions
  unused grammar symbols

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Simulation and Animation

• Models are not just pictures they are executable
  
• Interactive animation select next action,
  observe reaction
• Flexibility one-shot / step-wise forward /
  backward etc.
• Allows for
• Dynamic check of model correctness
• run under different test inputs similar to
  debugging
• Explore different derivation policies
• (left-most, right-most, use of backtracking)

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Transformations and Traceability

• Variety of transformations supported
• determinization and minimization of automata
• translation of grammar into a normal form
• conversions Automata ?? Regular Expressions
• Traceability show mapping between source and
  target models

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Selecting level of details

• Flexible use of the tool view all details vs.
  final result only
• Example (determinization) for given NDA, build
  equivalent DA
• Process
• Build your own solution
• Generate final answer with the tool compare it
  with yours
• (e.g. compare simulation results on the same
  inputs)
• Your solution is incorrect, reasons unclear?
• View all interim details, see what went wrong

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Share models to improve communication

• Attach model file when posting a question /
  homework
• Used by recipient both as doc executable
• replaces messy verbal description / makes it more
  clear
• can be checked and run
• easier to understand the question and to answer
  it
• Similar for assignment solutions published by
  tutor
• view simulate it to compare with your
  solution

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Summary of learning process improvements

• Better sense of learned concepts live
  tangible
• Thorough validation of solutions
• not just 1-2 paper-and-pencil checks
• Easy trial-and-error make changes, check their
  impact
• Levels of details leading to proper understanding
• Improved communication

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Further steps

• Improve integration into the learning process
• Extend the coverage of the course material
• - developed a script language
• for definition of lesson scenarios
• Assignments with mandatory use of the tools
• Levels of access to tools functions, according
  to course schedule
• Use of tools in synchronous teaching

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Interactive Tools for Teaching Automata and
Formal Languages

• Thanks for your attention