Next: Scripts
Up: Strong Slot and Filler
Previous: Strong Slot and Filler
Conceptual Dependency
originally developed to represent knowledge acquired from natural language
input.
The goals of this theory are:
- To help in the drawing of inference from
sentences.
- To be independent of the words used in the original input.
- That is to say: For any 2 (or more) sentences that are identical in
meaning there should be only one representation of that meaning.
It has been used by many
programs that portend to understand English (MARGIE, SAM, PAM). CD
developed by Schank et al. as were the previous examples.
CD provides:
- a structure into
which nodes representing information can be placed
- a specific set of
primitives
- at a given level of granularity.
Sentences are represented as a series of diagrams depicting actions
using both abstract and real physical situations.
- The agent and the objects are
represented
- The actions are built up from a set of primitive acts which
can be modified by tense.
Examples of Primitive Acts are:
- ATRANS
- -- Transfer of an abstract relationship. e.g. give.
- PTRANS
- -- Transfer of the physical location of an object. e.g. go.
- PROPEL
- -- Application of a physical force to an object. e.g. push.
- MTRANS
- -- Transfer of mental information. e.g. tell.
- MBUILD
- -- Construct new information from old. e.g. decide.
- SPEAK
- -- Utter a sound. e.g. say.
- ATTEND
- -- Focus a sense on a stimulus. e.g. listen, watch.
- MOVE
- -- Movement of a body part by owner. e.g. punch, kick.
- GRASP
- -- Actor grasping an object. e.g. clutch.
- INGEST
- -- Actor ingesting an object. e.g. eat.
- EXPEL
- -- Actor getting rid of an object from body. e.g. ????.
Six primitive conceptual categories provide building blocks which are the
set of allowable dependencies in the concepts in a sentence:
- PP
- -- Real world objects.
- ACT
- -- Real world actions.
- PA
- -- Attributes of objects.
- AA
- -- Attributes of actions.
- T
- -- Times.
- LOC
- -- Locations.
How do we connect these things together?
Consider the example:
John gives Mary a book
- Arrows indicate the direction of dependency. Letters above indicate
certain relationships:
- o
- -- object.
- R
- -- recipient-donor.
- I
- -- instrument e.g. eat with a spoon.
- D
- -- destination e.g. going home.
- Double arrows () indicate two-way links between the
actor (PP) and action (ACT).
- The actions are built from the set of primitive acts (see above).
So the past tense of the above example:
John gave Mary a book becomes:
The has an object (actor), PP and action, ACT. I.e.
PP ACT.
The triplearrow () is also a two link but between an object, PP, and
its attribute, PA. I.e. PP PA.
It represents isa type dependencies. E.g
Dave lecturerDave is a lecturer.
Primitive states are used to describe many state descriptions such as
height, health, mental state, physical state.
There are many more physical states than primitive actions. They use a numeric
scale.
E.g.
John height(+10) John is the tallest
John height(< average) John is
short
Frank Zappa health(-10) Frank Zappa
is dead
Dave mental_state(-10) Dave is sad
Vase physical_state(-10) The vase
is broken
You can also specify things like the time of occurrence in the relation ship.
For Example:
John gave Mary the book yesterday
Now let us consider a more complex sentence:
Since smoking can kill you, I stopped
Lets look at how we represent the inference that smoking can kill:
- Use the notion of one to apply the knowledge to.
- Use the primitive act of INGESTing smoke from a cigarette to one.
- Killing is a transition from being alive to dead. We use triple
arrows to indicate a transition from one state to another.
- Have a conditional, c causality link. The triple arrow
indicates dependency of one concept on another.
To add the fact that I stopped smoking
- Use similar rules to imply that I smoke cigarettes.
- The qualification attached to this dependency indicates that
the instance INGESTing smoke has stopped.
Advantages of CD:
- Using these
primitives involves fewer inference rules.
- Many inference rules are already
represented in CD structure.
- The holes in the initial structure help to focus on the points
still to be established.
Disadvantages of CD:
Applications of CD:
- MARGIE
- (Meaning Analysis, Response Generation and Inference on
English) -- model natural language understanding.
- SAM
- (Script Applier Mechanism) -- Scripts to understand stories.
See next section.
- PAM
- (Plan Applier Mechanism) -- Scripts to understand stories.
Schank et al. developed all of the above.
Next: Scripts
Up: Strong Slot and Filler
Previous: Strong Slot and Filler
dave@cs.cf.ac.uk