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1. # Describe The Language Denoted By The Following Regular Expressions

In this blog post, we are going to explore the language denoted by the following regular expressions: -(d+).(d{2}).(d{4}) The expression above denotes a number between one and four, with an optional two digits after the decimal point. For example, the expression “d{3}” would denote a number between 3 and 9.

## Regular Expressions

The language denoted by the following regular expressions is Perl.

Perl is a programming language that uses regular expressions to control how text is processed.

## The Degrees of Possibility

The expressions below denote different levels of possibility.

Regular Expressions with Unrestricted Variables:

The expressions below all have unrestricted variables. This means that the variables can take on any value.

This level of possibility is called “open”.

Regular Expressions with Restricted Variables:

The expressions below have restricted variables. This means that the variables can only take on certain values.

This level of possibility is called “closed”.

open = Unrestricted variables closed = Restricted variables

## Modifiers

The language denoted by the following regular expressions is a simple, pure functional language with an evaluation order that always proceeds from left to right.

The regular expression “a+b” matches any number of consecutive a’s and b’s. The expression “x*y” matches any number of x’s followed by any number of y’s. The language has no associative operations, so the order of evaluation is important. The expression “x+y” will evaluate to x+y regardless of the order in which x and y are evaluated.

Pure functional languages are very concise, but can also be difficult to understand for beginners. They have few built-in operators, so often developers must use functions from other languages to build their solutions. Additionally, the evaluation order means that problems can easily become compounded if calculations are not carried out in the correct order.

## Conjunction

The following expressions denote the language of regular expressions.

^(+|-)(d+)\$
The expression ^ matches the beginning of a string and \$ matches any character not in the string. The expression (+|-) matches either + or -, but not both. The expression d+ matches a single digit.

## Auxiliary Verbs

Regular expressions are used to identify strings of text using a set of rules. The following auxiliary verbs can be used in regular expressions:

-Be: indicates that the following word is a verb
-Have: indicates that the following word is a noun or an adjective
-Have Got: indicates possession (e.g. “John has a car”)

## Compound Forms

The language denoted by the following regular expressions is composed of two parts: a verb and a noun.

The verb in this language is “run”. The nouns are “runner” and “runners”.

## Irregular Verbs

Irregular verbs are verbs that do not follow the simple pattern of past, present, and future. There are many irregular verbs, but some of the most common include to be, to go, and to have.

To be is a regular verb, but its infinitive form is to be not. The present tense is formed by adding -es to the base form, for example, I am. The past tense is formed by removing -ed from the base form, for example, I was. The future tense is formed by adding -est to the base form, for example, I will be. To go is also a regular verb, but its infinitive form is to go not. The present tense is formed by adding -es to the base form, for example, she goes. The past tense is formed by removing -ed from the base form, for example she went. The future tense is formed by adding -est to the base form, for example she will go. To have is also a regular verb, but its infinitive form is to have not. The present tense is formed by adding -s to the base form, for example he has. The past tense is formed by removing -ed from the base form, for example he had.