To better understand, here is a definition of correspondence :
Given two sets A and B, there is a correspondence between them when a function every element of A has an image in B, and every element of B has a controimmagine in A.
So two together can be put into correspondence only when they have the same number of elements (cardinality).
Usually a report is a set of pairs generated by a proposition open to two variables p (x, y) becomes a function when each element of first set is present in at least a couple becomes a bijection when every element of the first or second set is present in only a couple.
Here's an example:
A = {A, B, C, D}
B = {1, 2, 3, 4, 5} With the following function
injection (one correspondence):
And the following bijective function (correspondence):
analysis of the two functions in the images we deduce that:
- In the first match is unique and the function is injective, because the domain of the function corresponds to all A same and every element x of A has a distinct image in B.
- The second correspondence is bijective and the function is bijective, since even the codomain corresponds to B and each element has associated with a single line item in the collection.
- The binary alphabet is B = {0, 1}, and a signal to be interpreted by the CPU or any electronic circuit, must be translated into an electrical signal with voltage, such as the voltage of 0 corresponds to the binary 0, 1 and 5 is the voltage rail. We have created a correspondence between the binary alphabet B = {0, 1} and the set of voltages Circuit considered V {0, 5}.
- A bijective function more complex can form between two classes of a school, 1B and 2C. 1B = {Mark, John, Michael, Lorenzo, Angela, Vanessa, Isabella and 2C} {Mary, Francis, Anna, Frances, Joseph, Simon, Luca}, a relation R: A → B given by p (x, y) "x is of the same sex y ' with x ∈ A and y ∈ B. R can be considered as a bijective function, it examined the set of pairs is obtained, analyzed the domain, codomain, and correspondence that you create.
- between two cars (Fiat Punto and Volkswagen Golf), if we consider the set of standard parts the first and second (ie every car should have. For example: front left wheel, front right, rear left, etc. ...), we can make a correspondence between the sets as each car has to have those pieces. But if we consider the total set of pieces of each car, we will not have a correspondence, and perhaps even a function.
0 comments:
Post a Comment