What is a ? B?
Hereof, what is a _firxam_#8710; B in sets?
usually denotes the operation of symmetric difference of two sets: if A and B are sets, A?B=(A∖B)∪(B∖A). In plain English, A?B is the set of things that belong to exactly one of A and B.
Just so, what is a Delta B?
The Delta B, or Thor-Delta B was an American expendable launch system used for nine orbital launches between 1962 and 1964. The first stage was a Thor missile in the DM-21 configuration, and the second stage was the Delta D, which was derived from the earlier Delta.
In mathematics, the symmetric difference, also known as the disjunctive union, of two sets is the set of elements which are in either of the sets and not in their intersection. The symmetric difference of the sets A and B is commonly denoted by. or. or. For example, the symmetric difference of the sets and is .