Machine Reading as a Process of Partial Question-Answering

Machine Reading as a Process ofPartial Question-Answering Peter Clark and Phil Harrison Boeing Research & Technology June 2010

Overview • Machine Reading and Question-Answering • Approach • Algorithm • Preliminary Results • Summary

Machine Reading • Machine Reading = • A “holy grail” of AI • Constructing an inference-supporting representation from text • Connecting what is read with what is already known • Reader already knows something • Text is elaborating/deepening that knowledge Machine Reading Do I already know this? Can I interpret this as something that I know? Can I interpret some of this as something I know?

Machine Reading Question-Answering Do I already know this? Can I interpret this as something that I know? Can I interpret some of this as something I know? Any remainder = failed query Machine Reading Do I already know this? Can I interpret this as something that I know? Can I interpret some of this as something I know? Any remainder = new knowledge

Machine Reading Question-Answering Main insight: These are similar processes Can apply question-answering techniques to machine reading. Why is that important? Question-answering is precisely a technology for linking what is said (asked) with what is known. Machine Reading i.e., To read text T Ask: Is it true that T?

General Approach “The mitotic spindle consists of hollow microtubules.” Text: Question: “Does the mitotic spindle consist of hollow microtubules?” Partial Answer: “Mitotic spindle has parts [hollow] microtubules” Knowledge has guided interpretation New Knowledge: “Those microtubules are hollow”

General Approach “The mitotic spindle consists of hollow microtubules.” Text: Question: “Does the mitotic spindle consist of hollow microtubules?” Partial Answer: “The mitotic spindle has parts [hollow] microtubules” ..and identified the “anchor points” in the KB for new knowledge New Knowledge: “Those microtubules are hollow”

General Approach “The mitotic spindle consists of hollow microtubules.” Text: Question: “Does the mitotic spindle consists of hollow microtubules?” Partial Answer: “The mitotic spindle has parts [hollow] microtubules” New Knowledge: “Those microtubules are hollow”

Pipelined (KB independent) NLP During prophase, the cell… Topic in the KB Parse, logical form Word-Sense Disambiguation ? Semantic Role Labeling

Interleaved Interpretation and Answering During prophase, the cell… Topic in the KB Logical Form

Interleaved Interpretation and Answering During prophase, the cell… Topic in the KB Logical Form Existing Knowledge

Interleaved Interpretation and Answering During prophase, the cell… Topic in the KB Logical Form Suppose this is the best we can do, interpreting text as existing knowledge

Interleaved Interpretation and Answering During prophase, the cell… Topic in the KB Logical Form Traditional NLP

Interleaved Interpretation and Answering During prophase, the cell… Topic in the KB Logical Form New Knowledge

Interleaved Interpretation and Answering During prophase, the cell… Topic in the KB Logical Form Extended KB

Interleaved Interpretation and Answering During prophase, the cell… Topic in the KB Logical Form Extended KB Word sense choices Semantic role choices Paraphrase rewrites

Some Possible Semantic Role Labels… “DNA synthesized by the polymerase” means? location? agent? KB

Some Possible Paraphrases (DIRT)… “spindle consists of microtubules” “spindle is staffed by microtubules” “microtubules are part of the spindle” “microtubules participate in the spindle” … KB

Knowledge Representation • Ontology: • ~400 biology concepts, ~400 general concepts • Axioms: • Mainly “Forall…exists…” axioms, e.g., • “All eukaryotic cells contain a nucleus” • “Subevents of mitosis are prophase, metaphase, …” • Inference: • Reason about an instance of a concept • Conclusions apply to all instances of the concept (via UG)

Topics Topic: Prophase • Topic = the concept that a text describes • We assume a text is about a single topic • Topic could be identified using ML (we do it by hand) • Given topic, can find (some) expected “participants” from KB The centrosomes are pushed apart to opposite ends of the cell nucleus by the action of molecular motors acting on the microtubules. The nuclear envelope breaks downm allowing….

Topics Topic: Prophase • Topic = the concept that a text describes • Participants = Individuals implied to exist given the topic • Can infer (some) participants using the KB The centrosomes are pushed apart to opposite ends of the cell nucleus by the action of molecular motors acting on the microtubules. The nuclear envelope breaks downm allowing…. Prophase • → centrosome moves to the pole of a eukaryotic cell • → nucleus, cytoplasm • → nuclear membrane, etc. etc. KB

Topics Topic: Prophase • Topic = the concept that a text describes • Participants = Individuals implied to exist given the topic • Can infer (some) participants using the KB The centrosomes are pushed apart to opposite ends of the cell nucleus by the action of molecular motors acting on the microtubules. The nuclear envelope breaks downm allowing…. Prophase • → centrosome moves to the pole of a eukaryotic cell • → nucleus, cytoplasm • → nuclear membrane, etc. etc. KB • Text provides information about participants

Algorithm Topic: Prophase • Identify the topic of the text • Parse and create initial “logical form” “The mitotic spindle consists of hollow microtubules.” "mitotic-spindle"(s), "consist"(c), "hollow"(h), "microtubule"(m), subject(c,s), "of"(c,m), modifier(m,h). 1. Setup Create representation of topic + (known) participants in KB 2. Search: repeat: interpret+ (try to) prove parts of the LF until: as much proved as possible Interpret remainder (normal NLP) and add to KB

“The mitotic spindle consists of hollow microtubules.” destination object Y1:Centrosome Y2:Eukaryotic-Cell Y0:Move subevent has-part has-region object X0:Prophase Y3:Elongate Y4:Mitotic-Spindle Y5:Pole has-part Y6:Create Y7:Microtubule … … Create a representation of the topic in the KB

“The mitotic spindle consists of hollow microtubules.” destination object Y1:Centrosome Y2:Eukaryotic-Cell Y0:Move subevent has-part has-region object X0:Prophase Y3:Elongate Y4:Mitotic-Spindle Y5:Pole has-part Y6:Create Y7:Microtubule … … Generate Logical Form LF interpretation: "mitotic-spindle"(s), "consist"(c), "hollow"(h), "microtubule"(m), subject(c,s), "of"(c,m), mod(m,h).

“The mitotic spindle consists of hollow microtubules.” destination object Y1:Centrosome Y2:Eukaryotic-Cell Y0:Move subevent has-part has-region object X0:Prophase Y3:Elongate Y4:Mitotic-Spindle Y5:Pole has-part Y6:Create Y7:Microtubule … … LF interpretation: "mitotic-spindle"(s), "consist"(c), "hollow"(h), "microtubule"(m), subject(c,s), "of"(c,m), mod(m,h). Interpret and (try) prove some part of the LF

“The mitotic spindle consists of hollow microtubules.” destination object Y1:Centrosome Y2:Eukaryotic-Cell Y0:Move subevent has-part has-region object X0:Prophase Y3:Elongate Y4:Mitotic-Spindle Y5:Pole has-part Y6:Create Y7:Microtubule … … LF interpretation: "mitotic-spindle"(s), "consist"(c), "hollow"(h), "microtubule"(m), subject(c,s), "of"(c,m), mod(m,h). isa(Y4,MSpindle), "consist"(c), "hollow"(h), "microtubule"(m), subject(c,Y4),"of"(c,m),mod(m,h) Bind a LF variable Interpret and (try) prove some part of the LF

“The mitotic spindle consists of hollow microtubules.” destination object Y1:Centrosome Y2:Eukaryotic-Cell Y0:Move subevent has-part has-region object X0:Prophase Y3:Elongate Y4:Mitotic-Spindle Y5:Pole has-part Y6:Create Y7:Microtubule … … LF interpretation: "mitotic-spindle"(s), "consist"(c), "hollow"(h), "microtubule"(m), subject(c,s), "of"(c,m), mod(m,h). isa(Y4,MSpindle), "consist"(c), "hollow"(h), "microtubule"(m), subject(c,Y4),"of"(c,m),mod(m,h)  ? isa(Y4,MSpindle), "hollow"(h), "microtubule"(m), material(Y4,m), mod(m,h). Interpret and (try) prove some part of the LF

“The mitotic spindle consists of hollow microtubules.” destination object Y1:Centrosome Y2:Eukaryotic-Cell Y0:Move subevent has-part has-region object X0:Prophase Y3:Elongate Y4:Mitotic-Spindle Y5:Pole has-part Y6:Create Y7:Microtubule … … LF interpretation: "mitotic-spindle"(s), "consist"(c), "hollow"(h), "microtubule"(m), subject(c,s), "of"(c,m), mod(m,h). isa(Y4,MSpindle), "consist"(c), "hollow"(h), "microtubule"(m), subject(c,Y4),"of"(c,m),mod(m,h) ? isa(Y4,MSpindle), "hollow"(h), "microtubule"(m), has-part(Y4,m), mod(m,h). Interpret and (try) prove some part of the LF

“The mitotic spindle consists of hollow microtubules.” destination object Y1:Centrosome Y2:Eukaryotic-Cell Y0:Move subevent has-part has-region object X0:Prophase Y3:Elongate Y4:Mitotic-Spindle Y5:Pole has-part Y6:Create Y7:Microtubule … … Recognized Old Knowledge LF interpretation: "mitotic-spindle"(s), "consist"(c), "hollow"(h), "microtubule"(m), subject(c,s), "of"(c,m), mod(m,h). isa(Y4,MSpindle), "consist"(c), "hollow"(h), "microtubule"(m), subject(c,Y4),"of"(c,m),mod(m,h) isa(Y4,MSpindle), "hollow"(h),"microtubule"(m), has-part(Y4,m), mod(m,h). Interpret and (try) prove some part of the LF

“The mitotic spindle consists of hollow microtubules.” destination object Y1:Centrosome Y2:Eukaryotic-Cell Y0:Move subevent has-part has-region object X0:Prophase Y3:Elongate Y4:Mitotic-Spindle Y5:Pole has-part Y6:Create Y7:Microtubule … … Recognized Old Knowledge LF interpretation: "mitotic-spindle"(s), "consist"(c), "hollow"(h), "microtubule"(m), subject(c,s), "of"(c,m), mod(m,h). isa(Y4,MSpindle), "consist"(c), "hollow"(h), "microtubule"(m), subject(c,Y4),"of"(c,m),mod(m,h) isa(Y4,MSpindle), "hollow"(h),"microtubule"(m), has-part(Y4,m), mod(m,h).  ! isa(Y4,MSpindle), "hollow"(h),isa(Y7,Microtubule), has-part(Y4,Y7), modifier(Y7,h). Interpret and (try) prove some part of the LF

“The mitotic spindle consists of hollow microtubules.” destination object Y1:Centrosome Y2:Eukaryotic-Cell Y0:Move subevent has-part has-region object X0:Prophase Y3:Elongate Y4:Mitotic-Spindle Y5:Pole has-part Y6:Create Y7:Microtubule … … LF interpretation: "mitotic-spindle"(s), "consist"(c), "hollow"(h), "microtubule"(m), subject(c,s), "of"(c,m), mod(m,h). isa(Y4,MSpindle), "consist"(c), "hollow"(h), "microtubule"(m), subject(c,Y4),"of"(c,m),mod(m,h) isa(Y4,MSpindle), "hollow"(h), "microtubule"(m), has-part(Y4,m), mod(m,h). isa(Y4,MSpindle), "hollow"(h), isa(Y7,Microtubule), has-part(Y4,Y7), modifier(Y7,h).

“The mitotic spindle consists of hollow microtubules.” destination object Y1:Centrosome Y2:Eukaryotic-Cell Y0:Move subevent has-part has-region object X0:Prophase Y3:Elongate Y4:Mitotic-Spindle Y5:Pole has-part Y6:Create Y7:Microtubule … … LF interpretation: "mitotic-spindle"(s), "consist"(c), "hollow"(h), "microtubule"(m), subject(c,s), "of"(c,m), mod(m,h). isa(Y4,MSpindle), "consist"(c), "hollow"(h), "microtubule"(m), subject(c,Y4),"of"(c,m),mod(m,h) Traditional NLP for the rest… isa(Y4,MSpindle), "hollow"(h), "microtubule"(m), has-part(Y4,m), mod(m,h). isa(Y4,MSpindle), "hollow"(h), isa(Y7,Microtubule), has-part(Y4,Y7), modifier(Y7,h). isa(Y4,MSpindle),isa(Y8,Hollow), isa(Y7,Microtubule), has-part(Y4,Y7),shape(Y7,Y8).

“The mitotic spindle consists of hollow microtubules.” destination object Y1:Centrosome Y2:Eukaryotic-Cell Y0:Move subevent has-part has-region object X0:Prophase Y3:Elongate Y4:Mitotic-Spindle Y5:Pole has-part shape Y6:Create Y8:Hollow Y7:Microtubule … … New Knowledge LF interpretation: "mitotic-spindle"(s), "consist"(c), "hollow"(h), "microtubule"(m), subject(c,s), "of"(c,m), mod(m,h). Add to the KB isa(Y4,MSpindle), "consist"(c), "hollow"(h), "microtubule"(m), subject(c,Y4),"of"(c,m),mod(m,h) isa(Y4,MSpindle), "hollow"(h), "microtubule"(m), has-part(Y4,m), mod(m,h). isa(Y4,MSpindle), "hollow"(h), isa(Y7,Microtubule), has-part(Y4,Y7), modifier(Y7,h). isa(Y4,MSpindle),isa(Y8,Hollow), isa(Y7,Microtubule), has-part(Y4,Y7),shape(Y7,Y8).

“The mitotic spindle consists of hollow microtubules.” destination object Y1:Centrosome Y2:Eukaryotic-Cell Y0:Move subevent has-part has-region object X0:Prophase Y3:Elongate Y4:Mitotic-Spindle Y5:Pole has-part shape Y6:Create Y8:Hollow Y7:Microtubule … … New Knowledge

Overview • Machine Reading and Question-Answering • Approach • Algorithm • Illustration and Preliminary Results • Summary

Illustration Input Text + Topic (here, Prophase): “During prophase, chromosomes become visible, the nucleolus disappears, the mitotic spindle forms, and the nuclear envelope disappears. Chromosomes become more coiled and can be viewed under a light microscope. Each duplicated chromosome is seen as a pair of sister chromatids joined by the duplicated but unseparated centromere. The nucleolus disappears during prophase. In the cytoplasm, the mitotic spindle, consisting of microtubules and other proteins, forms between the two pairs of centrioles as they migrate to opposite poles of the cell. The nuclear envelope disappears at the end of prophase. This signals the beginning of the substage called prometaphase.” Output Axioms (expressed in English): • In all prophase events: • The chromosome moves. • The chromatids are attached by the centromere. • The nucleolus disappears during the prophase. • The mitotic spindle has parts the microtubule and the protein. • The mitotic spindle is created between the centrioles in the cytoplasm. • The centrioles move to the poles. • The nuclear envelope disappears at the end. • Something signals.

Illustration Input Text: “During prophase, chromosomes become visible, the nucleolus disappears, the mitotic spindle forms, and the nuclear envelope disappears. Chromosomes become more coiled and can be viewed under a light microscope. Each duplicated chromosome is seen as a pair of sister chromatids joined by the duplicated but unseparated centromere. The nucleolus disappears during prophase. In the cytoplasm,the mitotic spindle, consisting of microtubules and other proteins, forms between the two pairs of centrioles as they migrate to opposite poles of the cell. The nuclear envelope disappears at the end of prophase. This signals the beginning of the substage called prometaphase.”  Output Axioms (expressed in English): Good interpretation using paraphrases • In all prophase events: • The chromosome moves. • The chromatids are attached by the centromere. • The nucleolus disappears during the prophase. • The mitotic spindle has parts the microtubule and the protein. • The mitotic spindle is created between the centrioles in the cytoplasm. • The centrioles move to the poles. • The nuclear envelope disappears at the end. • Something signals.

Illustration Input Text: “During prophase, chromosomes become visible, the nucleolus disappears, the mitotic spindle forms, and the nuclear envelope disappears. Chromosomes become more coiled and can be viewed under a light microscope. Each duplicated chromosome is seen as a pair of sister chromatids joined by the duplicated but unseparated centromere. The nucleolus disappears during prophase. In the cytoplasm,the mitotic spindle, consisting of microtubules and other proteins, forms between the two pairs of centrioles as they migrate to opposite poles of the cell. The nuclear envelope disappears at the end of prophase. This signals the beginning of the substage called prometaphase.”  Output Axioms (expressed in English): Useful New Knowledge • In all prophase events: • The chromosome moves. • The chromatids are attached by the centromere. • The nucleolus disappears during the prophase. • The mitotic spindle has parts the microtubule and the protein. • The mitotic spindle is created between the centrioles in the cytoplasm. • The centrioles move to the poles. • The nuclear envelope disappears at the end. • Something signals.

Illustration Input Text: “During prophase, chromosomes become visible, the nucleolus disappears, the mitotic spindle forms, and the nuclear envelope disappears. Chromosomes become more coiled and can be viewed under a light microscope. Each duplicated chromosome is seen as a pair of sisterchromatids joined by the duplicated but unseparatedcentromere. The nucleolus disappears during prophase. In the cytoplasm, the mitotic spindle, consisting of microtubules and other proteins, forms between the two pairs of centrioles as they migrate to opposite poles of the cell. The nuclear envelope disappears at the end of prophase. This signals the beginning of the substage called prometaphase.”  Output Axioms (expressed in English): Good interpretation • In all prophase events: • The chromosome moves. • The chromatids are attached by the centromere. • The nucleolus disappears during the prophase. • The mitotic spindle has parts the microtubule and the protein. • The mitotic spindle is created between the centrioles in the cytoplasm. • The centrioles move to the poles. • The nuclear envelope disappears at the end. • Something signals.

Illustration Input Text: “During prophase, chromosomes become visible, the nucleolus disappears, the mitotic spindle forms, and the nuclear envelope disappears. Chromosomes become more coiled and can be viewed under a light microscope. Each duplicated chromosome is seen as a pair of sister chromatids joined by the duplicated but unseparated centromere. The nucleolus disappears during prophase. In the cytoplasm, the mitotic spindle, consisting of microtubules and other proteins, forms between the two pairs of centrioles as they migrate to opposite poles of the cell. The nuclear envelope disappears at the end of prophase. This signalsthe beginning of the substage called prometaphase.”  Output Axioms (expressed in English): Not very useful • In all prophase events: • The chromosome moves. • The chromatids are attached by the centromere. • The nucleolus disappears during the prophase. • The mitotic spindle has parts the microtubule and the protein. • The mitotic spindle is created between the centrioles in the cytoplasm. • The centrioles move to the poles. • The nuclear envelope disappears at the end. • Something signals.

Illustration Input Text: “During prophase, chromosomes become visible, the nucleolus disappears, the mitotic spindle forms, and the nuclear envelope disappears. Chromosomes become more coiled and can be viewed under a light microscope. Each duplicated chromosome is seenas a pair of sister chromatids joined by the duplicated but unseparated centromere. The nucleolus disappears during prophase. In the cytoplasm, the mitotic spindle, consisting of microtubules and other proteins, forms between the two pairs of centrioles as they migrate to opposite poles of the cell. The nuclear envelope disappears at the end of prophase. This signals the beginning of the substage called prometaphase.”  Output Axioms (expressed in English): Bad interpretation • In all prophase events: • The chromosome moves. • The chromatids are attached by the centromere. • The nucleolus disappears during the prophase. • The mitotic spindle has parts the microtubule and the protein. • The mitotic spindle is created between the centrioles in the cytoplasm. • The centrioles move to the poles. • The nuclear envelope disappears at the end. • Something signals.

A Preliminary Experiment • 10 paragraphs (110 sentences) about prophase, from Web •  114 logic statements created • 23 (20%) fully known to the KB • 27 (24%) partially new knowledge • 64 (56%) completely new knowledge • Biologist ranked the statements (expressed in English) as: • c = correct; useful knowledge for the KB • q = questionable; not useful (meaningless, vague) • i = incorrect   

Machine Reading as a Process of Partial Question-Answering