2003, g.tecuci, learning agents laboratory 1 learning agents laboratory computer science department...
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1 2003, G.Tecuci, Learning Agents Laboratory
Learning Agents LaboratoryComputer Science Department
George Mason University
Prof. Gheorghe Tecuci
10 Multistrategy Learning10 Multistrategy Learning
2 2003, G.Tecuci, Learning Agents Laboratory
OverviewOverview
Introduction
Combining EBL with Version Spaces
Induction over Unexplained
Basic references
Guiding Induction by Domain Theory
Plausible Justification Trees
Research Issues
3 2003, G.Tecuci, Learning Agents Laboratory
Multistrategy learningMultistrategy learning
Multistrategy learning is concerned with developing learning agents that synergistically integrate two or more learning strategies in order to solve learning tasks that are beyond the capabilities of the individual learning strategies that are integrated.
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Examples
Learningfrom examples
Explanation-based learning
Multistrategy
Knowledge
many one several
learning
needed
Effect onagent'sbehavior
improves
competence
improves
efficiency
improvescompetence or/ and efficiency
Type ofinference induction deduction
induction and/ or deduction
Complementariness of learning strategiesComplementariness of learning strategies
complete incompleteknowledge
very littleknowledge
needed
Case Study:Inductive Learning vs Explanation-based Learning
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Multistrategy concept learningMultistrategy concept learning
Input
Background Knowledge (Domain Theory)
Goal
The Learning Problem
One or more positive and/or negative examples of a concept
Weak, incomplete, partially incorrect, or complete
Learn a concept description characterizing the example(s) and consistent with the background knowledge by combining several learning strategies
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Multistrategy knowledge base refinementMultistrategy knowledge base refinement
The Learning Problem:Improve the knowledge base so that the Inference Engine solves (classifies) correctly the training examples.
Similar names: background knowledge – domain theory – knowledge baseknowledge base refinement - theory revision
Training
Knowledge Knowledge BaseRefinement
Multistrategy
Examples
Base (DT)
InferenceEngine
KnowledgeBase (DT)
InferenceEngine
Improved
7 2003, G.Tecuci, Learning Agents Laboratory
Types of theory errors (in a rule based system)Types of theory errors (in a rule based system)
graspable(x) has-handle(x)
IncorrectKB (theory)
OverlySpecific
OverlyGeneral
MissingRule
ExtraRule
MissingPremise
AdditionalPremise
shape(x, round)
graspable(x) insulating(x)graspable(x)
width(x, small)& insulating(x)&
shape(x, round)graspable(x) width(x, small)
What is the effect of each error on the system’s ability to classify graspable objects, or other objects that need to be graspable, such as cups?
Proofs for some positive examples cannot be built:
Proofs for some negative examples can be built:
Positive examples that are not round, or have a handle
Negative examples that are round, or are insulating but not small
How would you call a KB where some positive examples are not explained (classified as positive)?
How would you call a KB where some negative examples are wrongly explained (classified as positive)?
+ + + _
Positive examples Negative examples
8 2003, G.Tecuci, Learning Agents Laboratory
OverviewOverview
Introduction
Combining EBL with Version Spaces
Induction over Unexplained
Basic references
Guiding Induction by Domain Theory
Plausible Justification Trees
Research Issues
9 2003, G.Tecuci, Learning Agents Laboratory
EBL-VS: Combining EBL with Version SpacesEBL-VS: Combining EBL with Version Spaces
• Apply explanation-based learning to generalize the positive and the negative examples.
• Replace each example that has been generalized with its generalization.
• Apply the version space method to the new set of examples.
Produce an abstract illustration of this algorithm.
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EBL-VS features EBL-VS features
• Learns from positive and negative examples
Justify the following feature, considering several cases:
• Apply explanation-based learning to generalize the positive and the negative examples.• Replace each example that has been generalized with its generalization.• Apply the version space method to the new set of examples.
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EBL-VS features EBL-VS features
Justify the following feature:
• Apply explanation-based learning to generalize the positive and the negative examples.• Replace each example that has been generalized with its generalization.• Apply the version space method to the new set of examples.
• Can learn with an incomplete background knowledge
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EBL-VS features EBL-VS features
Justify the following feature:
• Apply explanation-based learning to generalize the positive and the negative examples.• Replace each example that has been generalized with its generalization.• Apply the version space method to the new set of examples.
• Can learn with different amounts of knowledge, from knowledge-free to knowledge-rich
13 2003, G.Tecuci, Learning Agents Laboratory
EBL-VS features summary and references EBL-VS features summary and references
• Learns from positive and negative examples
• Can learn with an incomplete background knowledge
• Can learn with different amounts of knowledge, from knowledge-free to knowledge-richReferences
Hirsh, H., "Combining Empirical and Analytical Learning with Version Spaces," in Proc. of the Sixth International Workshop on Machine Learning, A. M. Segre (Ed.), Cornell University, Ithaca, New York, June 26-27, 1989.
Hirsh, H., "Incremental Version-space Merging," in Proceedings of the 7th International Machine Learning Conference, B.W. Porter and R.J. Mooney (Eds.), Austin, TX, 1990.
14 2003, G.Tecuci, Learning Agents Laboratory
OverviewOverview
Introduction
Combining EBL with Version Spaces
Induction over Unexplained
Basic references
Guiding Induction by Domain Theory
Plausible Justification Trees
Research Issues
15 2003, G.Tecuci, Learning Agents Laboratory
IOU: Induction Over Unexplained IOU: Induction Over Unexplained
Limitation of EBL-VS• Assumes that at least one generalization of an example is correct and complete
IOU• Knowledge base could be incomplete but correct: - the explanation-based generalization of an example may be incomplete; - the knowledge base may explain negative examples.• Learns concepts with both explainable and conventional aspects
Justify the following limitation of EBL-VS:
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IOU method IOU method
• Apply explanation-based learning to generalize each positive example
• Disjunctively combine these generalizations (this is the explanatory component Ce)
• Disregard negative examples not satisfying Ce and remove the features mentioned in Ce from all the examples
• Apply empirical inductive learning to determine a generalization of the reduced set of simplified examples (this is the non-explanatory component Cn)
The learned concept is Ce & Cn
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IOU: illustration IOU: illustration
Positive examples of cups: Cup1, Cup2
Negative examples: Shot-Glass1, Mug1, Can1
Domain Theory: incomplete - contains a definition of a generalization of the concept to be learned (e.g. contains a definition of drinking vessels but no definition of cups)
Ce = has-flat-bottom(x) & light(x) & up-concave(x) & {[width(x,small) & insulating(x)]has-handle(x)}
Ce covers Cup1, Cup2, Shot-Glass1, Mug1 but not Can1
Cn = volume(x,small)
Cn covers Cup1, Cup2 but not Shot-Glass1, Mug1
C = Ce & Cn
Mooney, R.J. and Ourston, D., "Induction Over Unexplained: Integrated Learning of Concepts with Both Explainable and Conventional Aspects,", in Proc. of the Sixth International Workshop on Machine Learning, A.M. Segre (Ed.), Cornell University, Ithaca, New York, June 26-27, 1989.
18 2003, G.Tecuci, Learning Agents Laboratory
OverviewOverview
Introduction
Combining EBL with Version Spaces
Induction over Unexplained
Basic references
Guiding Induction by Domain Theory
Plausible Justification Trees
Research Issues
19 2003, G.Tecuci, Learning Agents Laboratory
Enigma: Guiding Induction by Domain TheoryEnigma: Guiding Induction by Domain Theory
Limitations of IOU• Knowledge base rules have to be correct• Examples have to be noise-free
ENIGMA• Knowledge base rules could be partially incorrect• Examples may be noisy
Justify the following limitations of IOU:
20 2003, G.Tecuci, Learning Agents Laboratory
Enigma: methodEnigma: method
Trades-off the use of knowledge base rules against the coverage of examples:
• Successively specialize the abstract definition D of the concept to be learned by applying KB rules
• Whenever a specialization of the definition D contains operational predicates, compare it with the examples to identify the covered and the uncovered ones
• Decide between performing:- a KB-based deductive specialization of D- an example-based inductive modification of D
The learned concept is a disjunction of leaves of the specialization tree built.
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Enigma: illustrationEnigma: illustration
Examples (4 positive, 4 negative)
Positive example4 (p4):light(o4) & support(o4,b) & body(o4,a) & above(a,b) & up-concave(o4) Cup(o4)
Background Knowledge
Liftable(x) & Stable(x) & Open-vessel(x) Cup(x)
light(x) & has-handle(x) Liftable(x)
has-flat-bottom(x) Stable(x)
body(x, y) & support(x, z) & above(y, z) Stable(x)
up-concave(x) Open-vessel(x)
KB: - partly overly specific (explains only p1 and p2)- partly overly general (explains n3)
Operational predicates start with a lower-case letter
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Enigma: illustration (cont.)Enigma: illustration (cont.)
induction
deduction
Cup(x)
Liftable(x), Stable(x), Open-vessel(x)
has-flat-bottom(x)
light(x), has-handle(x)Stable(x),Open-vessel(x)
light(x)Stable(x),Open-vessel(x)
light(x),
Open-vessel(x)
light(x), body(x, y),
Open-vessel(x)
p1,p2,n3 p1,p2,p3,p4,n2,n3,n4
p1,p3,n2,n3 p2,p4,n4
support(x, z), above(y, z)
has-flat-bottom(x),light(x),
up-concave(x)
p1,p3,n2,n3
has-flat-bottom(x),light(x),
has-small-bottom(x)
p1,p3light(x), body(x, y),
up-concave(x)
p2,p4
support(x, z), above(y, z),
Open-vessel(x)
deduction
deductiondeduction induction
deduction
deduction
(to cover p3,p4)
(to uncover n2,n3)
Classification is based only on operational features:
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Learned conceptLearned concept
light(x) & has-flat-bottom(x) &has-small-bottom(x) Cup(x) Covers p1, p3
light(x) & body(x, y) & support(x, z) & above(y, z) & up-concave(x) Cup(x)
Covers p2, p4
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ApplicationApplication
• Diagnosis of faults in electro-mechanical devices through an analysis of their vibrations
• 209 examples and 6 classes
• Typical example: 20 to 60 noisy measurements taken in different points and conditions of the device
• A learned rule:
IF the shaft rotating frequency is w0 and the harmonic at w0 has high intensity and the harmonic at 2w0 has high intensity in at least two measurements
THEN the example is an instance of C1 (problems in the joint), C4 (basement distortion) or C5 (unbalance)
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Application (cont.)Application (cont.)
Comparison between the KB learned by ENIGMA andthe hand-coded KB of the expert system MEPS
Ambiguityof rules
ENIGMA
MEPS
Recognitionrate time
Development
1.21
1.46
0.95
0.95 18 months
4 months
Bergadano, F., Giordana, A. and Saitta, L., "Automated Concept Acquisition in Noisy Environments," IEEE Transactions on Pattern Analysis and Machine Intelligence, 10 (4), pp. 555-577, 1988.
Bergadano, F., Giordana, A., Saitta, L., De Marchi D. and Brancadori, F., "Integrated Learning in a Real Domain," in B.W. Porter and R.J. Mooney (Eds. ), Proceedings of the 7th International Machine Learning Conference, Austin, TX, 1990.
Bergadano, F. and Giordana, A., "Guiding Induction with Domain Theories," in Machine Learning: An Artificial Intelligence Approach Vollume 3, Y. Kodratoff and R.S. Michalski (Eds.), San Mateo, CA, Morgan Kaufmann, 1990.
26 2003, G.Tecuci, Learning Agents Laboratory
OverviewOverview
Introduction
Combining EBL with Version Spaces
Induction over Unexplained
Basic references
Guiding Induction by Domain Theory
Plausible Justification Trees
Research Issues
27 2003, G.Tecuci, Learning Agents Laboratory
MTL-JT: Multistrategy Task-adaptive Learning
based on Plausible Justification Trees
MTL-JT: Multistrategy Task-adaptive Learning
based on Plausible Justification Trees• Deep integration of learning strategies
Integration of the elementary inferences that are employed by the single-strategy learning methods (e.g. deduction, analogy, empirical inductive prediction, abduction, deductive generalization, inductive generalization, inductive specialization, analogy-based generalization).
• Dynamic integration of learning strategies
The order and the type of the integrated strategies depend of the relationship between the input information, the background knowledge and the learning goal.
• Different types of input
(e.g. facts, concept examples, problem solving episodes)
• Different types of knowledge pieces in the knowledge base
(e.g. facts, examples, implicative relationships, plausible determinations)
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MTL-JT: assumptionsMTL-JT: assumptions
Input:
• correct (noise free)• one or several examples, facts, or problem solving episodes
Knowledge Base:
• incomplete and/or partially incorrect• may include a variety of knowledge types (facts, examples, implicative or causal relationships, hierarchies, etc.)
Learning Goal:
• extend, update and/or improve the knowledge base so as to integrate new input information
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Plausible justification treePlausible justification tree
P (a,b)
P (a,c) P (d) P (b)
P (a,f) P (g,a) P (b,e)P (h)
. . . . . . . . . . . .
P (b)
P (a,b)
...
} Input fact
} Facts from KB
Different types of inference (deductive, analogical, abductive, etc.)
n
o
u
4
q
1 2 i
v w
A plausible justification tree is like a proof tree, except that some of individual inference steps are deductive, while others are non-deductive or only plausible (e.g. analogical, abductive, inductive).
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Learning methodLearning method
• For the first positive example I1:- build a plausible justification tree T of I1- build the plausible generalization Tu of T- generalize the KB to entail Tu
• For each new positive example Ii:- generalize Tu so as to cover a plausible justification tree of Ii- generalize the KB to entail the new Tu
• For each new negative example Ii:- specialize Tu so as not to cover any plausible justification of Ii- specialize the KB to entail the new Tu without entailing the previous Tu
• Learn different concept definitions:- extract different concept definitions from the general justification tree Tu
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Facts:terrain(Philippines, flat), rainfall(Philippines, heavy), water-in-soil(Philippines, high)
Examples (of fertile soil):soil(Greece, red-soil) soil(Greece, fertile-soil) terrain(Egypt, flat) & soil(Egypt, red-soil) soil(Egypt, fertile-soil)
Plausible determination:rainfall(x, y) >= water-in-soil(x, z)
Deductive rules:soil(x, loamy) soil(x, fertile-soil) climate(x, subtropical) temperature(x, warm) climate(x, tropical) temperature(x, warm) water-in-soil(x, high) & temperature(x, warm) & soil(x, fertile-soil)
grows(x, rice)
MTL-JT: illustration from GeographyMTL-JT: illustration from Geography
Knowledge Base
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Positive and negative examples of "grows(x, rice)"Positive and negative examples of "grows(x, rice)"
Positive Example 1:rainfall(Thailand, heavy) & climate(Thailand, tropical) & soil(Thailand, red-soil) & terrain(Thailand, flat) & location(Thailand, SE-Asia) grows(Thailand, rice)
Positive Example 2:rainfall(Pakistan, heavy) & climate(Pakistan, subtropical) & soil(Pakistan, loamy) & terrain(Pakistan, flat) & location(Pakistan, SW-Asia) grows(Pakistan, rice)
Negative Example 3:rainfall(Jamaica, heavy) & climate(Jamaica, tropical) & soil(Jamaica, loamy) & terrain(Jamaica, abrupt) & location(Jamaica, Central-America) ¬ grows(Jamaica, rice)
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Build a plausible justification of the first exampleBuild a plausible justification of the first example
water-in-soil(Thailand, high)
temperature(Thailand, warm)
soil(Thailand, fertile-soil)
rainfall(Thailand, heavy)
climate(Thailand, tropical)soil(Thailand, red-soil)
analogy
deductionand abduction
grows(Thailand, rice)
deduction
inductive prediction
Example 1:rainfall(Thailand, heavy) & soil(Thailand, red-soil) & terrain(Thailand, flat) & location(Thailand, SE-Asia) & climate(Thailand, tropical) grows(Thailand, rice)
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Build a plausible justification of the first exampleBuild a plausible justification of the first example
water-in-soil(Thailand, high)
temperature(Thailand, warm)
soil(Thailand, fertile-soil)
rainfall(Thailand, heavy)
climate(Thailand, tropical)soil(Thailand, red-soil)
analogy
deductionand abduction
grows(Thailand, rice)
deduction
inductive prediction
Example 1:rainfall(Thailand, heavy) & soil(Thailand, red-soil) & terrain(Thailand, flat) & location(Thailand, SE-Asia) &climate(Thailand, tropical) grows(Thailand, rice)
Justify the inferences from the above tree: analogy
Facts:terrain(Philippines, flat), rainfall(Philippines, heavy), water-in-soil(Philippines, high)
Plausible determination:rainfall(x, y) >= water-in-soil(x, z)
35 2003, G.Tecuci, Learning Agents Laboratory
Build a plausible justification of the first exampleBuild a plausible justification of the first example
water-in-soil(Thailand, high)
temperature(Thailand, warm)
soil(Thailand, fertile-soil)
rainfall(Thailand, heavy)
climate(Thailand, tropical)soil(Thailand, red-soil)
analogy
deductionand abduction
grows(Thailand, rice)
deduction
inductive prediction
Example 1:rainfall(Thailand, heavy) & soil(Thailand, red-soil) & terrain(Thailand, flat) & location(Thailand, SE-Asia) &climate(Thailand, tropical) grows(Thailand, rice)
Justify the inferences from the above tree: deduction
Deductive rules:soil(x, loamy) soil(x, fertile-soil) climate(x, subtropical) temperature(x, warm) climate(x, tropical) temperature(x, warm) water-in-soil(x, high) & temperature(x, warm) & soil(x, fertile-soil)
grows(x, rice)
36 2003, G.Tecuci, Learning Agents Laboratory
Build a plausible justification of the first exampleBuild a plausible justification of the first example
water-in-soil(Thailand, high)
temperature(Thailand, warm)
soil(Thailand, fertile-soil)
rainfall(Thailand, heavy)
climate(Thailand, tropical)soil(Thailand, red-soil)
analogy
deductionand abduction
grows(Thailand, rice)
deduction
inductive prediction
Example 1:rainfall(Thailand, heavy) & soil(Thailand, red-soil) & terrain(Thailand, flat) & location(Thailand, SE-Asia) &climate(Thailand, tropical) grows(Thailand, rice)
Justify the inferences from the above tree: inductive prediction & abduction
Examples (of fertile soil):soil(Greece, red-soil) soil(Greece, fertile-soil) terrain(Egypt, flat) & soil(Egypt, red-soil) soil(Egypt, fertile-soil)
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Multitype generalizationMultitype generalization
GENERALIZATION
grows(x1, rice)
water-in-soil(x1, high)temperature(x1, warm)
soil(x1, fertile-soil)
rainfall(x2, heavy) soil(x4, red-soil)
DEDUCTIVE
climate(x3, tropical)
DEDUCTIVE GENERALIZATION
GENERALIZATIONINDUCTIVE
ANALOGY
GENERALIZATIONBASED ON
|||water-in-soil(x2, high)
|||temperature(x3, warm)
soil(x4, fertile-soil)|||
38 2003, G.Tecuci, Learning Agents Laboratory
Multitype generalizationMultitype generalization
GENERALIZATION
grows(x1, rice)
water-in-soil(x1, high)temperature(x1, warm)
soil(x1, fertile-soil)
rainfall(x2, heavy) soil(x4, red-soil)
DEDUCTIVE
climate(x3, tropical)
DEDUCTIVE GENERALIZATION
GENERALIZATIONINDUCTIVE
ANALOGY
GENERALIZATIONBASED ON
|||water-in-soil(x2, high)
|||temperature(x3, warm)
soil(x4, fertile-soil)|||
Justify the generalizations from the above tree:
generalization based on analogy
Facts:terrain(Philippines, flat), rainfall(Philippines, heavy), water-in-soil(Philippines, high)
Plausible determination:rainfall(x, y) >= water-in-soil(x, z)
39 2003, G.Tecuci, Learning Agents Laboratory
Multitype generalizationMultitype generalization
GENERALIZATION
grows(x1, rice)
water-in-soil(x1, high)temperature(x1, warm)
soil(x1, fertile-soil)
rainfall(x2, heavy) soil(x4, red-soil)
DEDUCTIVE
climate(x3, tropical)
DEDUCTIVE GENERALIZATION
GENERALIZATIONINDUCTIVE
ANALOGY
GENERALIZATIONBASED ON
|||water-in-soil(x2, high)
|||temperature(x3, warm)
soil(x4, fertile-soil)|||
Justify the generalizations from the above tree:
Inductive generalization
Examples (of fertile soil):soil(Greece, red-soil) soil(Greece, fertile-soil) terrain(Egypt, flat) & soil(Egypt, red-soil) soil(Egypt, fertile-soil)
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Build the plausible generalization Tu of TBuild the plausible generalization Tu of T
GENERALIZATION
grows(x, rice)
water-in-soil(x, high)temperature(x, warm)
soil(x, fertile-soil)
rainfall(x, heavy) soil(x, red-soil)
DEDUCTIVE
climate(x, tropical)
DEDUCTIVE GENERALIZATION
GENERALIZATIONINDUCTIVE
ANALOGY
GENERALIZATIONBASED ON
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Positive example 2Positive example 2
Instance of the current Tu corresponding to Example 2
water-in-soil(Pakistan, high) temperature(Pakistan, warm) soil(Pakistan, fertile-soil)
rainfall(Pakistan, heavy) climate(Pakistan, tropical) soil(Pakistan, red-soil)
grows(Pakistan, rice)
analogy deduction
d e d u c t i o n
inductive prediction
falsefalse
Plausible justification tree T2 of Example 2:
water-in-soil(Pakistan, high) temperature(Pakistan, warm)
rainfall(Pakistan, heavy) climate(Pakistan, subtropical)
grows(Pakistan, rice)
analogy deduction
d e d u c t i o n
soil(Pakistan, fertile-soil)
soil(Pakistan, loamy)
deduction
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Positive example 2Positive example 2
The explanation structure S2:
The new Tu:
generalization
grows(x1, rice)
water-in-soil(x1, high)
temperature(x1, warm)
soil(x1, fertile-soil)
rainfall(x1, heavy)
climate(x1, tropical)
soil(x1, red-soil) soil(x3, loamy)
soil(x3, fertile-soil)
temperature(x2, warm)
climate(x2, subtropical)
deductive
generalizationdeductive
___
___
grows(x, rice)
deductive generalization
generalizationbased on analogy
water-in-soil(x, high) temperature(x, warm) soil(x, fertile-soil)
rainfall(x, heavy) climate(x, subtropical) soil(x, red-soil) soil(x, loamy)
or
climate(x, tropical)
or inductive deductivegeneralization
deductivegeneralization
deductivegeneralizationgeneralization
43 2003, G.Tecuci, Learning Agents Laboratory
Negative example 3Negative example 3
Instance of Tu corresponding to the Negative Example 3:
The new Tu:
analogydeduction
d e d u c t i o n
deduction
water-in-soil(Jamaica, high) temperature(Jamaica, warm) soil(Jamaica, fertile-soil)
rainfall(Jamaica, heavy)
climate(Jamaica, tropical)
soil(Jamaica, loamy)
grows(Jamaica, rice)
soil(Jamaica, red-soil)
orfalse
inductiveprediction
climate(Jamaica, subtropical)
or
false
deduction
water-in-soil(x, high)
rainfall(x, heavy) terrain(x, flat)
grows(x, rice)
deductive generalization
generalizationbased on analogy
temperature(x, warm) soil(x, fertile-soil)
climate(x, subtropical)soil(x, red-soil) soil(x, loamy)
or
climate(x, tropical)
or inductive deductivegeneralizationdeductive
generalizationdeductive
generalization
generalization inductivespecialization
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The plausible generalization tree
corresponding to the three input examples
The plausible generalization tree
corresponding to the three input examples
GENERALIZATIONS
grows(x, rice)
water-in-soil(x, high)temperature(x, warm)
soil(x, fertile-soil)
rainfall(x, heavy)
climate(x, subtropical)
soil(x, red-soil)
soil(x, loamy)
terrain(x, flat)
DEDUCTIVE
climate(x, tropical)
OROR
DEDUCTIVE GENERALIZATION
GENERALIZATIONINDUCTIVE
GENERALIZATIONDEDUCTIVEANALOGY
GENERALIZATIONBASED ON
SPECIALIZATION INDUCTIVE
45 2003, G.Tecuci, Learning Agents Laboratory
Learned knowledgeLearned knowledge
New facts:water-in-soil(Thailand, high)water-in-soil(Pakistan, high)
water-in-soil(Thailand, high) temperature(Thailand, warm) soil(Thailand, fertile-soil)
rainfall(Thailand, heavy) climate(Thailand, tropical) soil(Thailand, red-soil)
analogy deductionabduction
d e d u c t i o n
grows(Thailand, rice)
inductive prediction
water-in-soil(Pakistan, high) temperature(Pakistan, warm) soil(Pakistan, fertile-soil)
rainfall(Pakistan, heavy) climate(Pakistan, tropical) soil(Pakistan, red-soil)
grows(Pakistan, rice)
analogy deduction
d e d u c t i o n
inductive prediction
falsefalse
Why is it reasonable to consider these facts to be true?
46 2003, G.Tecuci, Learning Agents Laboratory
Learned knowledgeLearned knowledge
water-in-soil(Thailand, high) temperature(Thailand, warm) soil(Thailand, fertile-soil)
rainfall(Thailand, heavy) climate(Thailand, tropical) soil(Thailand, red-soil)
analogy deductionabduction
d e d u c t i o n
grows(Thailand, rice)
inductive prediction
Examples (of fertile soil):soil(Greece, red-soil) soil(Greece, fertile-soil) terrain(Egypt, flat) & soil(Egypt, red-soil) soil(Egypt, fertile-soil)
New plausible rule:soil(x, red-soil) soil(x, fertile-soil)
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Facts:terrain(Philippines, flat), rainfall(Philippines, heavy), water-in-soil(Philippines, high)
Learned knowledgeLearned knowledge
Specialized plausible determination:rainfall(x, y) & terrain(x, flat) >= water-in-soil(x, z)
GENERALIZATIONS
grows(x, rice)
water-in-soil(x, high)temperature(x, warm)
soil(x, fertile-soil)
rainfall(x, heavy)
climate(x, subtropical)
soil(x, red-soil)
soil(x, loamy)
terrain(x, flat)
DEDUCTIVE
climate(x, tropical)
OROR
DEDUCTIVE GENERALIZATION
GENERALIZATIONINDUCTIVE
GENERALIZATIONDEDUCTIVEANALOGY
GENERALIZATIONBASED ON
SPECIALIZATION INDUCTIVE
Positive Example 1:rainfall(Thailand, heavy) & climate(Thailand, tropical) & soil(Thailand, red-soil) & terrain(Thailand, flat) & location(Thailand, SE-Asia) grows(Thailand, rice)
Positive Example 2:rainfall(Pakistan, heavy) & climate(Pakistan, subtropical) & soil(Pakistan, loamy) & terrain(Pakistan, flat) & location(Pakistan, SW-Asia) grows(Pakistan, rice)
Negative Example 3:rainfall(Jamaica, heavy) & climate(Jamaica, tropical) & soil(Jamaica, loamy) & terrain(Jamaica, abrupt) & location(Jamaica, Central-America) ¬ grows(Jamaica, rice)
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Learned knowledge: concept definitionsLearned knowledge: concept definitions
Operational definition of "grows(x, rice)":rainfall(x,heavy) & terrain(x,flat) & [climate(x,tropical) climate(x,subtropical)] & [soil(x,red-soil) soil(x,loamy)]
grows(x, rice)
Abstract definition of "grows(x, rice)":water-in-soil(x, high) & temperature(x, warm) & soil(x, fertile-soil)
grows(x, rice)
water-in-soil(x, high)
rainfall(x, heavy) terrain(x, flat)
grows(x, rice)
deductive generalization
generalizationbased on analogy
temperature(x, warm) soil(x, fertile-soil)
climate(x, subtropical)soil(x, red-soil) soil(x, loamy)
or
climate(x, tropical)
or inductive deductivegeneralizationdeductive
generalizationdeductive
generalization
generalization inductivespecialization
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Learned knowledge: example abstractionLearned knowledge: example abstraction
Abstraction of Example 1:water-in-soil(Thailand, high) & temperature(Thailand, warm) & soil(Thailand, fertile-soil) grows(Thailand, rice)
water-in-soil(Thailand, high)
temperature(Thailand, warm)
soil(Thailand, fertile-soil)
rainfall(Thailand, heavy)
climate(Thailand, tropical)soil(Thailand, red-soil)
analogy
deductionand abduction
grows(Thailand, rice)
deduction
inductive prediction
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Features of the MTL-JT method and referenceFeatures of the MTL-JT method and reference
• Is general and extensible
• Integrates dynamically different elementary inferences
• Uses different types of generalizations
• Is able to learn from different types of input
• Is able to learn different types of knowledge
• Exhibits synergistic behavior
• May behave as any of the integrated strategies
Tecuci, G., "An Inference-Based Framework for Multistrategy Learning," in Machine Learning: A Multistrategy Approach Volume 4, R.S. Michalski and G. Tecuci (Eds.), San Mateo, CA, Morgan Kaufmann, 1994.
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Features of the MTL-JT methodFeatures of the MTL-JT method
• Integrates dynamically different elementary inferences
Justify the following feature:
GENERALIZATION
grows(x, rice)
water-in-soil(x, high)temperature(x, warm)
soil(x, fertile-soil)
rainfall(x, heavy) soil(x, red-soil)
DEDUCTIVE
climate(x, tropical)
DEDUCTIVE GENERALIZATION
GENERALIZATIONINDUCTIVE
ANALOGY
GENERALIZATIONBASED ON
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Features of the MTL-JT methodFeatures of the MTL-JT method
Justify the following features:
• May behave as any of the integrated strategies
Explanation-based learningMultiple-example explanation-based learning Learning by abductionLearning by analogyInductive learning from examples
What strategies should we consider for the presented illustration of MTL-PJT?
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MTL-JT as explanation-based learningMTL-JT as explanation-based learning
GENERALIZATION
grows(x, rice)
water-in-soil(x, high)temperature(x, warm)
soil(x, fertile-soil)
rainfall(x, heavy) soil(x, red-soil)
DEDUCTIVE
climate(x, tropical)
DEDUCTIVE GENERALIZATION
GENERALIZATIONINDUCTIVE
ANALOGY
GENERALIZATIONBASED ON
x, rainfall(x, heavy) water-in-soil(x, high)x, soil(x, red-soil) soil(x, fertile-soil)
Assume the KB would contain the knowledge:
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MTL-JT as abductive learningMTL-JT as abductive learning
x, rainfall(x, heavy) water-in-soil(x, high)
Assume the KB would contain the knowledge:
water-in-soil(Thailand, high)
temperature(Thailand, warm)
soil(Thailand, fertile-soil)
rainfall(Thailand, heavy)
climate(Thailand, tropical)soil(Thailand, red-soil)
analogy
deductionand abduction
grows(Thailand, rice)
deduction
inductive prediction
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MTL-JT as inductive learning from examplesMTL-JT as inductive learning from examples
grows(Thailand, rice)
rainfall(Thailand, heavy)climate(Thailand, tropical) soil(Thailand, red-soil)
location(Thailand, SE-Asia)
Positive Example 1:
grows(Pakistan, rice)
rainfall(Pakistan, heavy)climate(Pakistan, subtropical) soil(Pakistan, loamy)
location(Pakistan, SW-Asia)
Positive Example 2:
terrain(Thailand, flat)
terrain(Pakistan, flat)
grows(Jamaica, rice)
rainfall(Jamaica, heavy)climate(Jamaica, tropical) soil(Jamaica, loamy)
location(Jamaica, Central-America)
terrain(Jamaica, abrupt)
Negative Example 3:
grows(x, rice)
rainfall(x, heavy) terrain(x, flat)
Empirical Generalization:
¬
[soil(x, red-soil) or soil(x, loamy)][climate(x, tropical) or climate(x, subtropical)]
[location(x, SE-Asia) orlocation(x, SW-Asia)]
grows(Thailand, rice)
rainfall(Thailand, heavy)climate(Thailand, tropical) soil(Thailand, red-soil)
location(Thailand, SE-Asia)
Positive Example 1:
grows(Pakistan, rice)
rainfall(Pakistan, heavy)climate(Pakistan, subtropical) soil(Pakistan, loamy)
location(Pakistan, SW-Asia)
Positive Example 2:
terrain(Thailand, flat)
terrain(Pakistan, flat)
grows(Jamaica, rice)
rainfall(Jamaica, heavy)climate(Jamaica, tropical) soil(Jamaica, loamy)
location(Jamaica, Central-America)
terrain(Jamaica, abrupt)
Negative Example 3:
grows(x, rice)
rainfall(x, heavy) terrain(x, flat)
Empirical Generalization:
¬
[soil(x, red-soil) or soil(x, loamy)][climate(x, tropical) or climate(x, subtropical)]
[location(x, SE-Asia) orlocation(x, SW-Asia)]
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MTL-JT as analogical learningMTL-JT as analogical learning
Let us suppose that the KB contains only the following knowledge that is related to Example 1:
Facts: rainfall(Philippines, heavy), water-in-soil(Philippines, high)Determination: rainfall(x, y) --> water-in-soil(x, z)
Then the system can only infer that "water-in-soil(Thailand, high)", by analogy with "water-in-soil(Philippines, high)".
In this case, the MTL-JT method reduces to analogical learning.
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OverviewOverview
Introduction
Combining EBL with Version Spaces
Induction over Unexplained
Basic references
Guiding Induction by Domain Theory
Plausible Justification Trees
Research Issues
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Research issues in multistrategy learningResearch issues in multistrategy learning
• Comparisons of learning strategies
• New ways of integrating learning strategies
• Synergistic integration of a wide range of learning strategies
• The representation and use of learning goals in multistrategy systems
• Dealing with incomplete or noisy examples
• Evaluation of the certainty of the learned knowledge
• General frameworks for multistrategy learning
• More comprehensive theories of learning
• Investigation of human learning as multistrategy learning
• Integration of multistrategy learning and knowledge acquisition
• Integration of multistrategy learning and problem solving
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ExerciseExercise
Compare the following learning strategies:-Rote learning-Inductive learning from examples-Explanation-based learning-Abductive learning-Analogical learning-Instance-based learning-Case-based learningFrom the point of view of their input, background knowledge, type of inferences performed, and effect on system’s performance.
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ExerciseExercise
Identify general frameworks for multistrategy learning, based on the multistrategy learning methods presented.
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Basic referencesBasic references
• Proceedings of the International Conferences on Machine Learning, ICML-87, … , ICML-04, Morgan Kaufmann, San Mateo, 1987- 2004.
• Proceedings of the International Workshops on Multistrategy Learning, MSL-91, MSL-93, MSL-96, MSL-98.
• Special Issue on Multistrategy Learning, Machine Learning Journal, 1993.
• Special Issue on Multistrategy Learning, Informatica, vol. 17. no.4, 1993.
• Machine Learning: A Multistrategy Approach, Volume IV, Michalski R.S. and Tecuci G. (Eds.), Morgan Kaufmann, San Mateo, 1994.