universal set
Học thuậtThân thiện
Definition
- Noun:
- (Mathematics) The set containing all elements or objects relevant to a particular discussion or problem: In set theory, the universal set is the collection of every possible element that is being considered in a given context. It serves as the reference set from which all other sets in that context are formed.
Usage
- The universal set is a fundamental concept in set theory and probability. It defines the complete "universe of discourse" for a specific problem. All other sets within that problem are subsets of this universal set.
- It is often denoted by the symbols U, V, or ξ (xi).
Examples
- Noun:
- If we are discussing numbers between 1 and 10, the universal set U could be defined as {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}.
- In a survey about favorite fruits among students, the universal set would include every type of fruit that a student could potentially choose.
- The complement of a set A is defined with respect to the universal set; it contains all elements in the universal set that are not in A.
Advanced Usage
- Relative Nature: The definition of a universal set is not absolute but relative to the context. It changes depending on what is being studied. For example, the universal set for a geometry problem might be all points in a plane, while for an arithmetic problem it might be the set of all integers.
- In Probability: In probability theory, the universal set is often called the sample space (S), which represents all possible outcomes of an experiment.
Variants and Related Words
- Set (n): A well-defined collection of distinct objects.
- Subset (n): A set whose elements are all contained within another set (e.g., within the universal set).
- Complement (n): With respect to a universal set U, the complement of a set A is the set of elements in U that are not in A.
- Sample Space (n): (Probability) The set of all possible outcomes; functionally equivalent to the universal set in that context.
Synonyms
- Universe of discourse: The complete set of objects under consideration.
- Domain of discourse: The set of entities over which variables may range.
Related Concepts (Not Phrasal Verbs or Idioms)
- Venn Diagram: A diagram that uses circles to represent sets and their relationships, typically drawn within a rectangle that represents the universal set.
- Null Set / Empty Set: The set containing no elements, which is a subset of every set, including the universal set.
Noun
- (mathematics) the set that contains all the elements or objects involved in the problem under consideration
- all other sets are subsets of the universal set