An integrated modeling, debugging & visualization environment for g12

An integrated modeling, debugging & visualization environment for g12 Andreas Bauer, Viorica Botea, Mark Brown, Matt Gray, Daniel Harabor & John Slaney CP 2010, 522—536 Presented by Heath Roehr

Outline • The G12 Platform • Zinc: Constraint Modeling Language • The G12 IDE • Modeling Layer: Meet-Pass Scenario • Solving Layer • Visualization Layer • Debugging with the G12 IDE • Conclusion & Questions HEATH ROEHR

G12 Platform • Software platform for solving large-scale combinatorial optimization problems • Supports • Linear & mixed integer programming • Constraint propagation & inference • A variety of other search & inference techniques for solving complex problems HEATH ROEHR

Zinc: Modeling Language of G12 • Zinc is a first-order functional language with simple, declarative semantics • Modeling languages separate the constraint model from the constraint program • It provides • Mathematical notation-like syntax • Expressive constraints (finite domain and integer, set and linear arithmetic) • Separation of data from model • High-level data structures and data encapsulation including constrained types • User defined functions and constraints HEATH ROEHR

http://g12.research.nicta.com.au/zinc_current/index_home.php HEATH ROEHR

CP: Challenges • Solving • The problems are computationally challenging • Debugging? • Remember your homework... • Conceptualizing & improving search • Staring at code is not really the smartest strategy HEATH ROEHR

G12 IDE Debugging: Redefined Results: Visualized • Solving: Handled • Search • Constraint propagation Breakpoints: Controllable HEATH ROEHR

G12 IDE Architecture HEATH ROEHR

MODELING LAYER • Vector-oriented drawing tool • Associated script editor to • build custom animations Write constraint models in the input languages of G12 (Zinc & MiniZinc) HEATH ROEHR

MEET-PASS SCENARIO • Five sectors of railway track, S1, . . . S5, are linearly connected • There is a siding accessible from S3 big enough to hold one train S1 S2 S3 S4 S5 • Initially, there are trains in sectors S1, S2 and S4 Siding • The safety rules are that • No two trains may be in the same sector at the same time • No train may enter a sector occupied by another train, even if that other train is about to move on • Trains may only move to adjacent sectors, of course Constraints HEATH ROEHR

MEET-PASS SCENARIO • Find the shortest plan that moves the train on S1 to S5 and returns the other two trains to their starting positions. Initial Goal HEATH ROEHR

Meet-Pass Scenario: A possible Solution Step 0 HEATH ROEHR

Meet-Pass Scenario: A possible Solution Step 18: Solution Found HEATH ROEHR

ZINC EDITOR: MEET-PASS IMPLEMENTATION • Five sectors of railway track, S1, . . . S5, are linearly connected • There is a siding accessible from S3 big enough to hold one train • Initially, there are trains in sectors S1, S2 and S4 • Move the train on S1 to S5 and return the other two trains to their starting positions. HEATH ROEHR

ZINC EDITOR: MEET-PASS IMPLEMENTATION • Safety rules • Specific implementation is outside the scope of this talk • Assume they are accurate and valid • Execute the search HEATH ROEHR

ZINC EDITOR: MEET-PASS IMPLEMENTATION Variable Declaration Constraints Variable Definition HEATH ROEHR

ZINC EDITOR: SCREENSHOT Syntax highlighting Outline views Project-based code management HEATH ROEHR

VISUALIZATION EDITOR • Define arbitrary visualizations • Vector-based graphics editor • Script editor • Scripting language • Any language that supports java integration • Python • Lisp • Default language is Lua • Lightweight • Portable • Suited for animation: used in video games HEATH ROEHR

VISUALIZATION EDITOR Vector-based graphics editor Graphics properties editor Project-based code management HEATH ROEHR

VISUALIZATION EDITOR • g12GetFromData(var) • This method fetches the current contents of the decision variable var and makes its value available to the script. • g12Draw(obj, props) • This method sets a list of properties, props, for object obj, where props may contain items such as the object’s positions on the canvas, color, opacity, scaling factor, etc. Written in Java Written in Lua HEATH ROEHR

SOLVING LAYER Control the starting & stopping of the solving process Collect detailed information about the solving process The actual solver HEATH ROEHR

SOLVING LAYER XML-based messaging Separate Processes HEATH ROEHR

VISUALIZATION LAYER Build & display a constraint graph Pre-defined visualizations Build & display a search tree Render visualization based on custom animation script HEATH ROEHR

Sample Pre-Defined Visualizations Constraint Graph Search Tree Collapsed sub tree Domain split HEATH ROEHR

DEBUGGING WITH THE VISUALIZATION EDITOR Pre-defined visualizations & custom animations drawn in real-time, as the program executes HEATH ROEHR

HOW IS DEBUGGING DIFFERENT IN THE G12 IDE? • Debugging tools are by default associated with code at the native level • Example: set a breakpoint at line 59 in function “Y” • Instead, abstract away the native code & debug at a conceptual level • Example: set a breakpoint when the domain of variable “X” is empty • Operates on the constraint model, not the constraint program HEATH ROEHR

USER DEFINED BREAKPOINT VIEW User defined breakpoints “Search Events” (Events that induce the breakpoint) The breakpoint “subscribes” to these search events Enable/disable breakpoints HEATH ROEHR

Take it to the next level: Domain-specific animated debugging HEATH ROEHR

CUSTOM VISUALIZATION AND ANIMATION • Accomplished by • drawing objects • binding their animation to events that fire during program execution • Debugging is happening • At the conceptual level • Graphically: Domain-specific HEATH ROEHR

“MEET-PASS” EXAMPLE Propagation should deduce the position of the train… Original formulation failed to deduce correctly, identifying an incorrect constraint model… HEATH ROEHR

RELATED WORK • IDEs tailored to CSP solving • ECLiPSE CLP • Draw charts and graphs for solver output • ILOG OPL Studio • Offers a search-tree view similar to that of the G12 IDE • Choco • Java based visualizations from scratch • Vector-based graphics processing programs • Most are more advanced than G12’s graphics processor • Using a custom visualization tool that is tightly integrated with debugging facilities is novel HEATH ROEHR

An integrated modeling, debugging & visualization environment for g12