Posts Tagged ‘Semantics’

PostHeaderIcon Modality As A Semantic Category


Introduction

Based on the principle of differentiation of levels in linguistic analysis the term mood stands for a syntactic category and modality can be regarded as a semantic term. Thus in the following sample from the paradigm for the Sanskrit word /ksip/ = throw, three moods are distinguished, namely indicative, imperative and potential.

Voice-Active; Number-Singular; Person-1,2 & 3.

Indicative (Pres) Imperative Potential
ksipaami ksipaani ksipeyam
ksipasi ksip ksipes
ksipati ksipatu ksipet

However each of these mood forms can be used to convey a number of different types of messages. For example, the Imperative can be used in the First Person as part of the syntactic device along with a question word /kim/ to ask a question like

(1) kim karvaani te? (What should I do for you?)

One is not justified in positioning an Interrogative Mood for Sanskrit in so far as there is no particular morphological element in the verb characterizing the particular type of message: a question in this case. Instead one should speak of an interrogative message type, where the imperative mood form is used in conjunction with a question word: thee latter explicitly specifying what type of a message is intended.

There is an obvious parallel between mood taken in this sense and tense. Tense, although essentially related to the concept of time is purely a syntactic category.

He is coming now (I can see it).
And
He is coming next year.

Both of these sentences use the same tense: the present tense. But they refer to two different times, one the actual present and the other, future.

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PostHeaderIcon Universal Networking Language (UNL)

Universal Networking Language (UNL) is an Interlingua developed by UNDL foundation. UNL is in the form of semantic network to represent and exchange information. Concepts and relations enable encapsulation of the meaning of sentences. In UNL, a sentence can be considered as a hypergraph where each node is the concept and the links or arcs represent the relations between the concepts. UNL knowledge base provides concepts for the words in the natural language sentences.

The UNL consists of Universal Words (UWs), Relations and Attributes and knowledge base.

Universal Words (UWs)

Universal words are UNL words that carry knowledge or concepts. UWs are simply nodes in the UNL graph. There are two type of UWs: permanent and temporary. Permanent UWs represent concepts of common use and are included in the UW dictionary. Temporary UWs may represent new concepts, too specific or not translatable so that they are not included in the dictionary.

Examples:

bucket(icl>container)
water(icl>liquid)

Relations

Relations are labelled arcs that connect nodes (Uws) in the UNL graph. The relations are binary and usually represent semantic cases and semantic roles.

Examples:

agt ( break(agt>thing,obj>thing), John(iof>person) )

Attributes

Attributes are annotations used to represent grammatical categories, mood, aspect, etc. Every attribute starts with “@” symbol.

Example:

work(agt>human).@past
– means that the tense of the verb work is past tense, that is , it is actually worked in the sentence.

Knowledge Base

The UNL Knowledge Base contains entries that define possible binary relations between UWs.

PostHeaderIcon Semantic Roles

What are semantic roles?

Semantic roles, also known as thematic roles, are one of the oldest classes of constructs in linguistic theory. Semantic roles are used to indicate the role played by each entity in a sentence and are ranging from very specific to very general. The entities that are labelled should have participated in an event. Some of the domain-specific roles are from airport, to airport, and depart time. Some of the verb-specific roles are eater and eaten for the verb eat. Although there is no consensus on a definitive list of semantic roles some basic semantic roles such as agent, instrument, etc are followed by all.

Examples of Semantic Roles

AGENT

Agent is one who performs some actions. AGENT is a label representing the role of an agent.

Joe played well and won the price.
Here, Joe is the person who did playing.

CAUSE

Cause is one that causes something or it is a reason for some happenings.
Rain makes me happy.
Here, rain causes happiness and so is the cause.

EXPERIENCER

One who experienced is experiencer.
Johan felt very painful when heard of the sudden demise of his friend.
Here, Johan experienced the pain so he is the experiencer.

BENEFICIARY

I prayed early in the morning for Susan.
Here Susan is the beneficiary.

LOCATION

Steve was swimming in the river.
Needless to say river is the location.MANNER

Tom behaved very gently even when he was insulted.
Here gently should be labelled as manner.

INSTR

Tom broke the wooden box with the hammer.
Here hammer is the instrument used to break the wooden box

Specific Roles

FROM-LOC

means from location.

John received the prize from the President.

TO-LOC

means to location.

Susan threw a pen to John.

AT-LOC

This label means at location.

The box contains a ball.

AT-TIME

This label means at time.

I woke up at 5o clock to prepare for the examination.

Verbs typically specify upto three inner roles and There are syntactic relations on how various roles can be realized. Some of the examples are

AGENT only
Joe walked.

AGENT + INSTR
Where INSTR means instrument

Joe flies with a parchute.

Joe is agent and parachute is instrument.

AGENT + INSTR + BENEFICIARY
Joe flies with a parachute for charity.
Charity is the beneficiary.

Inner Roles

To classify verbs, a distinction should be made between roles that are closely related to the verb and those that are not. For example most of the past tense verbs allow AT-TIME role realized by the adverb yesterday. Therefore AT-TIME is obviously more a property of verb phrases in general than a property of any individual verb. On the other hand, other semantic roles, those realized by constituents for which the verb subcategorizes seem to be properties of the verb. For example, the verb put subcategorizes for a preposition, moreover this preposition must realize the TO-LOC role. In verb classification this latter type of role is important, and these roles are called the inner roles of the verb. So for a given verb if the role is obligatory then it is an inner role. There are inner roles that are optional as well. All verbs may take at most one noun phrase in any given inner role. Multiple noun phrases must be related by conjunction. The following sentence is valid.

Jack and Jill went to the hill.

But the following sentence is invalid.

*Jack Jill went to the hill.
Note that it is customary to put * before the invalid sentences.

Similarly the following sentence is valid.

Jack went to the school and to the playground.

Here the conjunction and used to relate the two noun phrases.

But the following sentence is invalid.

*Jack went to the school to the playground.

So in the above valid sentences AGENT (Jack) and TO-LOC (to the hill, to the school) are the inner roles for the verb went.

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