QC-Trees: An Efficient Summary Structure for Semantic OLAP

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Constrained Objects for Modeling Complex Systems
Pallavi Tambay, Yang Zhang, Prof. Bharat
Jayaraman
Constrained Objects gt Constraints Objects
What is a Constrained Object?

• Constraint languages
• Constraints model behavior
• - No resemblance to structure
• - Complex system is a flat collection of
  constraints
• - Constraints cannot be visualized
• Object-oriented languages
• Objects model structure
• - Methods not appropriate for modeling behavior
  of complex systems
• Visualization tools
• Natural, intuitive geometric representation
• - No representation of semantics or behavior of
  system
• - Modeler may not understand underlying
  representation

• An object is a container of data that is
  accessed via a well-defined interface of
  procedures. (Imperative)
• A constrained object contains data that is
  governed by laws, or constraints. (Declarative)
• Examples resistor in a circuit, a joint in a
  truss, a cell in a spreadsheet, etc.
• Cob is a programming language combining
  Java-like
• classes with declarative constraints instead of
  methods.

Principles underlying Constrained Objects

• Compositional specification of structure
• ? objects
• Declarative specification of behavior
• ? constraints
• Visual specification of structure ?
  smart diagrams

Typical Modeling Scenario
modeling define_Cob_classes
build_object_structu
re solve_structure
modify_structure
re_solve_structure
query_structure
Truss as Constrained Object
CUML Constraint-based UML (with R. Jyotwani)
class joint attributes bar Bars
load Loads constraints (sum X
in Bars X.B.F sin(X.A)) (sum
L in Load L.F sin(L.A)) 0 (sum Y
in Bars Y.B.F cos(Y.A)) (sum
M in Loads M.F cos(M.A)) 0 constructor
joint(B1, L1) Bars B1 Loads
L1
Domain-Specific Visual Language (with A. Dev
N. Menon)
class slab attributes level Pl beam
Peripherialbeams real Z constraints
forall B in Peripheralbeams B.Z Z
constructor slab(L,B) Pl L
Peripherialbeams B
Compilation and Execution
What is Partial Evaluator
Input
o
P
CCLP
-
translation of a Cob Program

G
CCLP
-
translation of a Cob Query

Evaluate
parEval(
G
, ,
C
)
o
Output
o
C
Set of constraints

P
C
G

?

Partial Evaluator (PE) - Strategy
parEval(true, C, C). parEval((A,B), Cin, Cout)
- parEval(A, Cin, Cout1),
parEval(B, Cout1, Cout). parEval(G, C, C) -
(clp_built-in(G) unification(G)
cob_builtin(G)), call(G).