What is CPS 140?

• upperlevel computer science course

• more theoretical, proofs

• different than most CPS courses for ugrads

• traditionally taught with all written homeworks

What have I done to this course?

• more visual and interactive

• use software tools to solve problems

• get feedback via software

Example: Represent finite automaton

Set Format

Tabular Format

Graphical Format

Interact with Automata

• create your own automata with JFLAP

• test it out with different data

• turn it in electronically

Solution to Presenting Theoretical Concepts

• Organization

• Visualization

• Interaction

Does this Help?

• see several representations (textual and visual)

  relate to mathematical notation in proofs

• more practice

  create additional problems to solve

Example: Modeling using L-Systems

What are L-Systems?

• grammatical systems to describe biological development

  growth of plants and cellular organisms

• created by Lyndenmayer

• composed of three parts

  alphabet:	set of symbols
  rewriting rules:	replace symbols
  axiom:	starting point

• use software tools to generate

  • lsys - Duke

  • StarLogo - (hatch turtles)

Creating an L-System with lsys

• Drawing Rules

  • g - move forward one step while drawing

  • f - move forward one step without drawing

  • X, Y - replacement symbols
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  

• Example Lsys Program:

  SET axiom X 
  X ==> g f g X
  
  SET d 15               % length of line
  SET iniwidth 5         % width of line
  SET color black
  

  
  
  
  
  
  
  
  

  Language of grammar is:

      X, gfgX, gfggfgX, gfggfggfgX ...
  

  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
• Another Example Lsys Program:

  SET axiom X             % start symbol is X
  
  X ==> g g g X + Y  
  Y ==> g 
  
  SET d 15                % length of line
  SET iniwidth 5          % width of line
  SET angle 15            % angle for change of direction 
  
  SET color blue 
  

  
  
  
  
  
  
  
  

  Language of grammar is:

     X, gggX+Y, ggggggX+Y+g, gggggggggX+Y+g+g, ggggggggggggX+Y+g+g+g ...
  

  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  

Student L-Systems