A “word” is a string of characters that can have different
meanings (jaguar: car or animal?; driver: one who
drives a vehicle or the part of a computer?; rows, the plural
noun or the third singular person of the verb to row?). A
“sentence” is a group of words that express a specific thought:
to capture it, we need to understand how words relate to other words (“Paul,
Jack’s brother, is married to Linda“. Linda is married to Paul, not
Jack.).
To understand word meaning and sentence meaning,
our semantic disambiguator engine must be able to automatically resolve
ambiguities to understand the meaning of each word in a text.
Every word has some meaning (some only in
context).
What is a meaning of a word? Consider some
candidates:
Dictionary definition
transmission:
1a. The act or process of transmitting.
1b. The fact of being transmitted.
2. Something, such as a message, that is transmitted.
3. An automotive assembly of gears and associated
parts by which power is transmitted from the engine to a driving
axle. Also called gearbox.
4. The sending of a signal, picture, or other
information from a transmitter.
But:
– to understand meaning of one word, you have
to know the meanings of other words.
– definitions often circular
• Mental image
But:
– Different people have different mental images
of the same words.
– Usually it is an image of some prototype.
– It is hard to
find mental images for some words (the, he,
aspect).
• Reference – The meaning of a word is
the actual thing in the real word.
Works for chair, house, etc.
But:
– tooth fairy, unicorn,
abstract nouns (history), adjectives (big), etc.
– different expressions with the same reference
Vaclav Klaus and the
current Czech president refer to the same object, so in this view, they
should have the same meaning. But:
1. If they had the same meanings, one should be
replaceable by the other.
Peter does not know that Vaclav Klaus is the
current Czech president. (OK)
Peter does not know that Vaclav Klaus is Vaclav
Klaus. (strange)
2. Intuitively, these expressions have
different meaning.
• Parallel worlds – works,
but quite complicated and not very intuitive. One world says how things really
are, the other worlds say how things could be. Meaning of a word is the
collection of it’s references in all worlds.
In some worlds, Vaclav Klaus is the current Czech
president, in some he is not.
Therefore in this theory, Vaclav
Klaus and the current Czech president have different meanings, as we
want.
Knowing the meaning of words is not enough to understand
the meaning of a sentence:
• Two sentences with the same words can mean
something different:
(1) a. A tourist eats a tiger.
b. A tiger
eats a tourist.
• Two sentences with some of the words
different can mean the same:
(2) a. A tiger eats a tourist.
b. A
tourist is eaten by a tiger.
You must know that in English:
• In active sentences, the one who does something
precedes the verb.
(3) A tiger eats a tourist.
eater eaten
eater eaten
• In passive sentences, the one who does something
follows the verb and has a preposition by.
(4) A tourist is eaten by a tiger.
eaten eater
eaten eater
