Multipurpose ITS 김계현 Intelligent Multimedia Lab.

Current State And Future Works Up To Now… Modularize the system Build whole running sequence Concrete designed modules Inference process => Just implement Make some examples Some grammars for NL recognition => Make whole grammars and Implement parser Need to be more concrete… Knowledge Base + Knowledge Generator Student Model Generator => Once implement, and then revise them

System Overview

Knowledge Base & Generator Concept-Relation Network Example: “The referencing environment is the collection of all names that are visible” => The referencing environment – (B) is (=equal to) the collection of all names - (C) that are (=and) visible – (D) => B ≡ C & D

Knowledge Base & Generator (cont’d)

“Visible” – (D) Can be referenced in that statement – (E) Possible to see – (F) => D ≡ E, D ≡ F

Knowledge Base & Generator (cont’d) Use Inference Engine Make Assumptions: => B ≡ C & D => B ≡ C & E( ∵ D ≡ E) => B ≡ C & F( ∵ D ≡ F) Questions and Answers: “Is it true that the referencing environment is collection of all names that can be referenced in that statement ?” – “Yes ” “Is it true that ~ all names that is possible to see ?” – “No ”

Knowledge Base & Generator (cont’d) “The referencing environment is the collection of all names that are visible” (Visible means, “Can be referenced in that statement”)

Inference Engine Discourse-level Understanding Use Proof-Based Understanding Technique (from Why2-Atlas)

Proof-Based Understanding Technique Discourse-level understanding by interaction with the Knowledge Base Query(KB, p)=> Proof(Right or Wrong)

Proof-Based Understanding: One Example Problem: Suppose you are running in a straight line at constant speed. You throw a pumpkin straight up. Where will it land? Explain. Korean Translation: 당신은 호박을 들고 등 속도로 달리고 있습니다. 이 상태에서 호박 을 하늘로 똑바로 던지면 어디로 떨어질까 요 ?

Correct Answer Correct Answer : Falls on my hands

One Answer Of A Certain Student Once the pumpkin leaves my hand, the horizontal force that I am exerting on it no longer exists, only a vertical force (caused by my throwing it). As it reaches it's maximum height, gravity (exerted vertically downward) will cause the pumpkin to fall. Since no horizontal force acted on the pumpkin from the time it left my hand, it will fall at the same place where it left my hands.

One Answer Of A Certain Student (cont’d) Two misconceptions horizontal force that I am exerting on 등속도로 움직이는데도 힘을 가한다고 믿고 있음 explicit misconception fall at the same place where it left 힘을 가하지 않으면 속도가 줄어든다고 믿고 있음 implicit misconception – 문맥 속에 숨어있는 misconception

Existing Method: Statistical Approach Latent Semantic Analysis, Naïve Bayes Recognize NL sentences using the pattern matching Find some “Important” (relative to the expected answer) words Evaluate the answer by the number of the words

Misunderstanding Problem Once the pumpkin leaves my hand … it will fall at the same place where it left my hands. (Wrong answer) High information value (relative to the expected answer) : fall, my, hands Statistical approaches conclude that the answer is Right

New Approach: Proof-Based Understanding Do Not Have Predefined answers Instead, Analyze the answer in this way: Translate each NL sentence to FOL proposition and for the each proposition, Find Evidence Quary(KB, proposition) Output: Correctness of the proposition and (sometimes) New Fact

Analyzing Each Sentence Once the pumpkin leaves my hand, the horizontal force that I am exerting on it no longer…. Proposition: Before the release, the man is holding the pumpkin (=> Right) Evidence: Given Problem

Misconception Is Detected …leaves my hand, the horizontal force that I am exerting on it no longer exists, only a vertical force… Proposition: The man exerts a nonzero horizontal force on the pumpkin (=>Wrong!) Evidence: ∀ x [ Say( x, [ ∀ y ∀ z InContact(y, z) => ExertsForce(y, z)] ) => HasMisconception(x) ]

Further Analysis …only a vertical force (caused by my throwing it)…. Proposition: After the release, nothing is touching the pumpkin Evidence: Given Problem

Further Analysis (cont’d) …Since no horizontal force acted on the pumpkin from the time it left my hand,… Proposition: After the release, the horizontal force is zero Evidence: ∀ x ∀ y, ￢ InContact(x,y) ∧￢ ExtremelyHeavy(x) ∧￢ ExtremelyHeavy(y) => CantExertForceOn(x,y) ∧ CantExertForceOn(y,x)

Further Analysis (cont’d) …the time it left my hand, it will fall at the same place where it left my hands. Proposition: The pumpkin’s initial & final positions are equal Evidence: ∀ x ZeroDisplacement(x)  Equals(InitialPosition(x), FinalPosition(x))

Analyzing the propositions It is not sufficient consequence for decision of correctness (could not find implicit misconception) Previous Proposition: The pumpkin’s initial & final positions are equal New Proposition: The pumpkin’s horizontal velocity is zero Evidence: ∀ x ∃ t velocity(x) = displacement(x) /time(t)

Analyzing the propositions (cont’d) Other Proposition: Pumpkin’s initial velocity is equal to that of the man (Given Problem) Evidence: ∀ x ∀ y, InContact(x,y) => velocity(x) = velocity(y)

Analyzing the propositions (cont’d) Combine the two propositions The pumpkin’s horizontal velocity is zero Pumpkin’s initial velocity is equal to that of the man Consequence: Pumpkin’s horizontal velocity is decreased Evidence: Former two propositions are treated as true

Other Misconception Is Detected Previous Proposition: After the release, the horizontal force is zero Previous Consequence: Pumpkin’s horizontal velocity is decreasing => Conflicts! Evidence: Newton’s First Law ∀ x ∀ t1 ∀ t2 ∀ t3 ∀ t4 (t1< t2) ∧ ForceOnDuring(x,t1,t2) = 0  (t1<t3 < t4< t2) ∧ (VelocityAt(x,t3)=VelocityAt(x,t4))

Student Model Generator Numeric Information 정답을 말할 때까지 걸린 시간, 한 문제당 오 답을 말한 횟수 등 Instructor need to provide some criteria 각 criterion 은 vector space 상에서 하나의 좌표축 이 됨 Use unsupervised clustering method Mixture of Gaussian with arbitrary covariance matrix How to decide K-value?

Student Model Generator (cont’d) Linguistic Information 철수는 축구를 좋아한다. 영희는 여행을 많이 다녀 견문이 넓다. 영수는 수학을 특히 못한 다. …. 취미, 배경지식 등이 같은 학생끼리 Group 을 만들 수 있음 K value 의 크기는 최소한 여기서 만들어진 Group 의 개수보다는 크다고 가정

Student Model Generator (cont’d) Interaction 어떤 group 에 속하는 학생들 중 얼마나 많은 학생들이 같은 cluster 에 속하는지 살핌 결과의 판정 = cluster 상에서 각 group 의 variance 의 총합 결과가 좋지 않으면 K value 를 1 증가시키고 다시 clustering Maximum K value = 전체 학생 수 /2

Student Model Generator (cont’d) Numeric criteria = 2, Linguistic group = 3

Student Model Generator (cont’d) Planning 지도 방법 및 순서 강의 진도는 자연히 맞춰짐 이 system 에서는 action list 로서 정의 Action: ( 질문, 정답 ) or ( 설명 ) Do 질문 1, if ( 정답 1) then Do 질문 2, if ( 정답 2) then … Do 질문 k, if (! 정답 k) break 각 cluster 별로 plan 을 관리 use, update

Student Model Generator (cont’d) Example – 관성의 법칙 Plan ( 이 학생은 요리가 취미이니 호박을 예로 들자.) 힘이 작용하지 않을 때 물체의 속도는 ? – ( 등속 ) 힘의 작용 방향이 속도와 반대방향일 때 속도는 ? – ( 감소 ) 속도가 0 이 되고 나서도 계속 힘이 작용하면 ? –( 힘의 방향으로 속도가 증가 ) Execution 선생 : 등속으로 뛰고 있던 사람이, 들고있던 호박을 수직으로 위로 던지면, 호박의 수평 속도는 얼마가 되니 ? 학생 : 0 이요. (Unexpected)

Student Model Generator (cont’d) Misconception 이 학생은 호박에 수평방향의 힘이 작용하고 있다고 생각한다. Misconception 을 바로잡기 위한 새로운 plan 을 삽입 New plan 호박에 작용한 힘은 무엇인가 ? – ( 공기저항 ) 공기저항은 없다고 가정한다. 다른 힘은 ? – ( 없다 ) 호박의 수평 속도는 어떻게 되는가 ? –( 등속 )

Student Model Generator (cont’d) Execution 선생 : 너랑 등속도로 움직이던 호박의 속도가 0 이 되었다 … 그러면, 호박에 무언가 힘이 작 용했다는 거네 ? 학생 : 아니요. (Unexpected) Misconception 이 학생은 물체에 힘이 작용하지 않아도 물체 의 속도가 변할 수 있다고 생각한다. New plan ….

Natural Language Recognizer Use Context-Sensitive Grammar (History) (Current State) (Future Plan) => Given String Parsing 은 이와 반대로 이루어지므로, 현재 가지고 있는 history 와 plan 에 대해 production rule 이 정의된 string 이 주어지면 reduce 한다.

Natural Language Recognizer (cont’d) => => ‘down’ | ‘downwards’ | ‘towards earth’