KNOWLEDGEBASED DESIGN

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KNOWLEDGE-BASED DESIGN

• Representation and Reasoning 2

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REPRESENTING DESIGNS AND DESIGN KNOWLEDGE

• designs
• goals
• knowledge
• Objects (as things) Facts
• Relationships between objects Knowledge

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OBJECTS AS FACTS

• ObjectAttributeValue OAV

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ATTRIBUTES AS OBJECTS
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CLASSES AND INSTANCES

• My house is a kind of (ako) house
• Yellow is a kind of (ako) colour
• This representation allows for inheritance

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OBJECTS AND RELATIONS

• Comparative relations
• Room 1 is smaller than Room 2
• View A is better than View B
• Structural relations
• A wall is a part of (apo) a room
• A room is a part of (apo) a house

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• Taxonomic relations
• A chair belongs to furniture
• A TV belongs to entertainment systems
• Topological relations
• The bathroom is next to the bedroom
• The attic is on top of the bedroom

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• Commutative relations
• Wall A is same length as Wall B
• Wall B is same length as Wall A
• Reciprocal relations
• Room A is bigger than Room B
• Room B is smaller than Room A

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RULES

• IF antecedant THEN consequent
• IF (A) THEN (C)
• IF (A and B) THEN (C)
• IF (A or B) THEN (C)
• IF (O-A-V) THEN (O-A-V)

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• IF (Roof Material IS tile) THEN (Roof IS
  waterproof)
• IF (Roof Material IS tile) THEN (Roof slope IS
  greater than 15 degrees)
• IF (Title CONTAINS http)THEN (OPEN URL)
• IF (Rain) THEN (TAKE umbrella)

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PRODUCTION SYSTEMS
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PRODUCTION SYSTEMS RULE-BASED REASONING

• IF antecedant THEN consequent
• IF (A) THEN (C)
• IF (A and B) THEN (C)
• IF (A or B) THEN (C)
• IF (O-A-V) THEN (O-A-V)

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• IF (Roof Material IS tile) THEN (Roof IS
  waterproof)
• IF (Roof Material IS tile) THEN (Roof slope IS
  greater than 15 degrees)
• IF (Title CONTAINS http)THEN (OPEN URL)
• IF (Rain) THEN (TAKE umbrella)

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Components of a Production System
Rules
Controller
Facts
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REASONING WITH RULES

• Replace algebraic operations with CHAINING
• goal-driven
• data-driven
• IF (A) THEN (B)
• IF (B) THEN (C)
• IF (B) THEN (D)
• IF (D) THEN (E)
• IF (D) THEN (F)

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• Given E is desired can it be achieved?
• Set E as goal and search rules for any rule that
  produces it
• IF (D) THEN (E)
• Reset goal to D and search rules for any rule
  that produces it
• IF (B) THEN (D)
• Reset goals to B and search rules for any rule
  that produces it
• IF (A) THEN (B)
• Is A known? If yes, then E can be produced.

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Breadth-First Search
Data-driven
Goal-driven
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Depth-First Search
Data-driven
Goal-driven
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Designs
Rules
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SEMANTIC NETS AND FRAMES

• Semantic nets
• Adds semantic labels to arcs of a graph
• Can construct your own semantics
• Reasoning through implementations of the
  semantics
• Frames
• Isomorphic with semantic nets
• Different representation

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A semantic network for describing classes
and instances of a house
building
ako
gt1
house
living in
use
floors
ako
1
floors
single-storydwelling
is a
roof colour
walls
my house
red
brick
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A class frame for a house
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A hierarchy of structural beam types
beam
ako
ako
staticallydeterminatebeam
staticallyindeterminatebeam
ako
ako
cantileverbeam
continuous beam
ako
ako
simplysupportedbeam
fixed-endbeam
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Relationships for which there is a communicating
medium
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PREDICATE LOGIC AS REPRESENTATION

• Predicate label (arguments)
• either statement of fact
• or converts a goal into subgoals
  which can eventually be
  mapped on to facts and the
  truth of subgoals deduced and
  hence the truth of goal can be
• deduced

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COMPUTING SISTER

• In English
• A sister is a female who shares the same parents
  as another person
• More precisely
• A female is a sister of another person if they
  both have the same parents
• Symbolically
• X is a sister if X is female and has same parents
  as Y.

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• sister (X,Y) if X is female and X has parents M
  and D and Y has parents M and D
• sister (X,Y) - female (X),
• parents (X, M, D,)
• parents (Y, M, D),
• X ? Y

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Design Using Predicate Logic as a Search Mechanism

• Write a program for designing an architectural
  unit obeying the following specifications
• Two rectangular rooms
• Each room has a window and interior door
• Rooms are connected by interior door
• One room also has an exterior door
• No window can face north
• Windows cannot be on opposite sides of the unit

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• direction(north).direction(south).direction(e
  ast).direction(west).opposite(north,south).opp
  osite(south,north).opposite(east,west).opposite(
  west,east).notopposite(D1,D2)-
  opposite(D1,D3), D2\D3.

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• room(D,W)- direction(D), direction(W),
  D\W, W\north.

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• Logic program
• plan(FD,D1,W1,D2,W2)- frontroom(FD,D1,W1),
• opposite(D1,D2),
• room(D2,W2),
• notopposite(W1,W2).frontroom(FD,D,W)- roo
  m(D,W),
• direction(FD),
• FD\W, W\north.

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• Planning a unit entered from the west
• ? plan (west, D1, W1, D2, W2)
• D1 west, W1 south, D2
  east, W2 south

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FD given
D2
D1
W1
W2
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• Checking whether a design meets therequirements
• ? plan(west, north, south, north, south)
• fails

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Check whether a design meets therequirements ?
plan(north, north, west, south, west) yes
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