1 of 20 23rd annual workshop on qualitative reasoning (qr 2009) ljubljana, slovenia, june 22 - 24,...
TRANSCRIPT
1 of 20
23rd Annual Workshop on Qualitative Reasoning (QR 2009) Ljubljana, Slovenia,June 22 - 24 , 2009
Model Building Experiences using Garp3: Problems, Patterns and
Debugging
Jochem Liem, Floris E. Linnebank & Bert BredewegHuman-Computer StudiesUniversity of Amsterdam
2 of 20
23rd Annual Workshop on Qualitative Reasoning (QR 2009) Ljubljana, Slovenia,June 22 - 24 , 2009
Motivation: Usability to Formalization Bottleneck• Availability of usable QR tools has led to:– More domain experts formalizing their conceptual
knowledge– The creation of more complex models
• Usability is no longer an issue• However, knowledge formalization is the new
bottleneck• Modelers encounter similar representational
issues, and reinvent solutions • This paper categorizes representation issues and
their solutions.
3 of 20
23rd Annual Workshop on Qualitative Reasoning (QR 2009) Ljubljana, Slovenia,June 22 - 24 , 2009
Trained Groups in QR Modelling• PhD-level researchers (NaturNet-Redime)– 2,5 year working with Garp3– Trainings each half year– Support using Skype/Flashmeeting
• BSc. Students (Future Planet Studies)– 4 weeks: Concept maps, Ontologies– 4 week: QR modelling (Carbon Cycle)
• PhD-students (School for Information and Knowledge Systems)– 1 hour lecture + 2 hour practical: Tree & Shade model
4 of 20
23rd Annual Workshop on Qualitative Reasoning (QR 2009) Ljubljana, Slovenia,June 22 - 24 , 2009
Entities or Quantities?
• Alternative representations:– Algae entity with Biomass
quantity– Algea concentration quantity
• Create a new entity when properties of this entity are important.
• E.g. photosynthesis quantity of the algae
Model by Elena Nakova , Yordan Uzunov
5 of 20
23rd Annual Workshop on Qualitative Reasoning (QR 2009) Ljubljana, Slovenia,June 22 - 24 , 2009
Configuration direction & naming
• Model by Richard Noble, Floris E. Linnebank & Bert Bredeweg
• Prefer active voice over passive voice• Shorter configuration names• Improves texts based on QR models
6 of 20
23rd Annual Workshop on Qualitative Reasoning (QR 2009) Ljubljana, Slovenia,June 22 - 24 , 2009
Relation reification
• Configuration direction is arbitrary• Long configuration name• Where to model speed of symbiosis process?
• Model by Paulo Salles & Bert Bredeweg
7 of 20
23rd Annual Workshop on Qualitative Reasoning (QR 2009) Ljubljana, Slovenia,June 22 - 24 , 2009
Influences & Proportionalities
Q1[+,-] Q2[+,?]I+
Q1[+,-] Q2[+,?]I-
Q1[-,-] Q2[+,?]I+
Q1[-,0] Q2[+,?]I-
8 of 20
23rd Annual Workshop on Qualitative Reasoning (QR 2009) Ljubljana, Slovenia,June 22 - 24 , 2009
Causal Interactions
Q1[+,-] Q2[+,?]I+
Q1[+,-] Q2[+,?]I-
Q1[-,-] Q2[+,?]I+
Q1[-,0] Q2[+,?]I-
Q3[-,-]I+
Q3[-,-]I+
Q3[-,-]I-
Q3[-,-]I-
9 of 20
23rd Annual Workshop on Qualitative Reasoning (QR 2009) Ljubljana, Slovenia,June 22 - 24 , 2009
Causal Chains
• Causal path: Influence followed by proportionalities• Rare: Multiple influences in a single causal path• Impossible: Loop of proportionalities
10 of 20
23rd Annual Workshop on Qualitative Reasoning (QR 2009) Ljubljana, Slovenia,June 22 - 24 , 2009
Multiple Competing Influences• CO2 release I+ CO2 Concentration • Burning I+ Co2 Concentration• Inequality information does not help
• Burning + CO2 concentration > 0• Introduce Photosynthesis• Burning + CO2 < Photosynthesis
11 of 20
23rd Annual Workshop on Qualitative Reasoning (QR 2009) Ljubljana, Slovenia,June 22 - 24 , 2009
Choosing Quantity Spaces• Difficult task even for expert modelers• Should be behaviorally significant• Depends depends on the context: – Phytoplankton blocking sunlight of 1st producers– Global warming’s effect on phytoplankton
12 of 20
23rd Annual Workshop on Qualitative Reasoning (QR 2009) Ljubljana, Slovenia,June 22 - 24 , 2009
{Small, Medium, High} considered harmful
13 of 20
23rd Annual Workshop on Qualitative Reasoning (QR 2009) Ljubljana, Slovenia,June 22 - 24 , 2009
Actuators: External actuator (1/3)
• Models (effect of) process outside the system– Value assignment (MF)
– Exogenous behaviour (Scenario)
• Model by Eugenia Cioaca, Tim Nuttle, Bert Bredeweg
14 of 20
23rd Annual Workshop on Qualitative Reasoning (QR 2009) Ljubljana, Slovenia,June 22 - 24 , 2009
Actuators: Equilibrium Seeking Mechanism (2/3)
• Models equalizing flows due to potential difference
15 of 20
23rd Annual Workshop on Qualitative Reasoning (QR 2009) Ljubljana, Slovenia,June 22 - 24 , 2009
Actuators: Competing Processes Pattern (3/3)
• Models competing processes
16 of 20
23rd Annual Workshop on Qualitative Reasoning (QR 2009) Ljubljana, Slovenia,June 22 - 24 , 2009
States in simulation• Maximum number of states:– Cartesian product of all quantities– E.g. Three Q’s: (3x3)3=729 (excl. inequalities)
• Successor states without correspondences:– S-states = 2q-1, q = non-corresponding quantities
17 of 20
23rd Annual Workshop on Qualitative Reasoning (QR 2009) Ljubljana, Slovenia,June 22 - 24 , 2009
Not all expected states• Issue: State is missing• Create the state as a scenario– Option 1: No states, state is inconsistent– Option 2: State appears
• Next create a scenario that generates a previous state
• Continue to a state in the original simulation
18 of 20
23rd Annual Workshop on Qualitative Reasoning (QR 2009) Ljubljana, Slovenia,June 22 - 24 , 2009
No States• Considered difficult to debug• Features:– Inconsistency– > 1 model fragment fired– Clash between contents of:
• Scenario + MF • Multiple MFs
• Troubleshooting:– Deactivate all MFs (at least 1 state from scenario)– Activate MFs one by one
19 of 20
23rd Annual Workshop on Qualitative Reasoning (QR 2009) Ljubljana, Slovenia,June 22 - 24 , 2009
Inconsistencies
• Magnitude or derivative value assignments (MF or scenario)
• Inequalities (MF or Scenario)
• Operators (plus or minus)
• Value assignments due to correspondences
• Value assignments due to influence resolution
• Exogenous behavior• Engine rules• Quantity constraints• Continuity constraints
20 of 20
23rd Annual Workshop on Qualitative Reasoning (QR 2009) Ljubljana, Slovenia,June 22 - 24 , 2009
Conclusions & Future Work• Catalog of – Representational issues and their solutions– Frequently occurring patterns – Considerations when debugging
• Future work: Support in Garp3/DynaLearn– Premade patterns (QS’s and actuators)– Automatic model building– Model diagnosis