1.2 Linguistic Variables as Words or Terms

1.2 Linguistic Variables as Words or Terms

Here for the first time, we describe linguistic variables only by words, develop and define them.

We illustrate linguistic variables in terms of linguistic words by some examples.

Example 1.2.1. Let us consider the linguistic variable “speed of a vehicle on road”. Let S be the linguistic set associated with this variable,

S = {very fast, fast, just fast, fastest, medium speed, slow, just medium, very slow, just slow, } here the term  means the empty linguistic word/term corresponding to zero 0 of the number system, that is no words.

Here if we take any two linguistic terms from S we can compare them like slow and fast where

“slow is a lesser speed than fast”;

slow  fast

medium and just slow

just slow  medium and so on.

Example 1.2.2. Let us consider the linguistic variable “colour” and not shades of a particular colour.

Let S be the linguistic set associated with the linguistic variable colour.

S = {black, blue, green, white, brown, red, orange}.

We cannot compare any of the two colours.

Comparison of colours is possible only if shades of a colour say like dark blue, blue, light blue, white shaded blue and so on.

Next, we give yet another example.

Example 1.2.3. Let us consider the linguistic variable height of persons. The linguistic set or linguistic terms associated with height is as follows.

S = {tall, very tall, very very tall, just tall, short, shortest, just short, very short, medium, just medium}.

We study the linguistic set S later and define operations on them.

Example 1.2.4. Let us consider the linguistic variable overgrowth (height, colour of leaves and so on) of paddy plants. Let S be the linguistic set associated with it.

S = {good, average, very good, bad, not up to the mark, very bad, just bad, just good and so on}.

Example 1.2.5. Let us consider the linguistic variable temperature of water while heating from ice state. The linguistic terms S associated with this variable is as follows.

S = {high, very low, highest, lowest,  (corresponds to 0 degree), low, just low, and so on}.

Now we can also have linguistic variables in social problems like school dropouts, unemployment as a societal problem, symptom disease model, etc.

Example 1.2.6. The social problem of unemployment among the educated youth is the linguistic variable. The linguistic terms associated with it are

S = {educated criminals, frustration, taking up to drugs, taking to violence, distress, mental stress, emptiness of life and so on}.

Example 1.2.7. Let us consider the linguistic variable school dropouts in children. Let S be the linguistic term,

S = {bonded labourers, runaways from home, family problems (parents in fault) rag pickers, bonded labourers}. This social problem can be given linguistic representation.

Example 1.2.8. Now we deal with the diagnostic problem of disease symptom model for lung infection, which is taken as the linguistic variable.

Let S be the set of linguistic terms.

S = {l1 - temperature in the evening

l2 - cold and fever

l3 - only cough

l4 - cough and fever

l5 - breathlessness