A restriction is a limit.
Restriction is a notion with an etymological origin in the Latin restrictĭo . It is the process and consequence of restricting . This verb , for its part, refers to limiting, adjusting, narrowing or circumscribing something.
For example: "The government announced a restriction on the import of chemical products with the aim of promoting national production" , "This literary contest does not set any restrictions on the length of the works" , "The organizers of the conference will establish a time restriction so that the speakers do not exceed their presentations" .
Shortage restriction
It is common for authorities to impose restrictions on the purchase of certain products when there is a shortage . The aim is to prevent the products in question from running out and becoming unavailable.
Suppose that, for various reasons, the quantity of milk on sale in a country is small. To prevent hoarding by some, which would lead to shortages for others, the government establishes a purchase restriction: each person can only buy three litres of milk per week. This measure seeks to distribute the available stock equitably.
In some contexts, restriction implies a prohibition .
Other classes
Restriction, in general, always sets a limit. A young person who has to take an exam to enter a university is given a maximum of two hours to complete it. This means that there is a restriction on completing the exam: the applicant cannot take more than two hours to complete the test. If he or she does not comply with the restriction, his or her evaluation is not accepted.
In genetics, the term endonuclease or restriction enzyme is used to refer to a molecule that is capable of detecting a certain sequence of nucleotides in a DNA molecule and then dividing the DNA at that precise point, which is known as a target or restriction site , or at a nearby part. In order to be recognized, these sites can have a number of base pairs ranging from four to six .
Restriction in mathematics
In mathematics , a restriction of a function to another function is defined in a subset of the domain of the initial function (the domain is, in turn, a set that contains the values for which a function is defined), and which does not entail a change with respect to the values assigned to each element. It is correct to say that the function to which this restriction is applied is an extension of the resulting function.
Let’s look at an example of this concept: if we have a set of people of all ages and another set of movie titles that have been released in the last ten years, and a function relates them by graphing what each person’s favorite title is, we can apply a restriction that only takes into account individuals whose age range is between 30 and 40, in order to focus on the tastes of that generation; this view has limits at both extremes, since it ignores people younger than 30 and older than 40, so the initial function can be considered an extension of this one, because it shows a greater number of relationships (in fact, it shows all of them).
As we have seen so far, it is necessary to reduce the domain of a function in order to obtain one of its possible reductions. On the contrary, the term extension can also be used to talk about a function that contemplates a larger domain, although always with the condition of not varying the images of the first (also called range or field of values , the image is the set of values that a given function can take).