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# cardinality

«cardinality» in Mova's school dictionary: **The number of things in a set or group** — its meaning for a pupil, its sense in the lessons and examples.

### part of speech

noun (cardinality, cardinalities)

### meaning for a pupil

1) (maths) The number of things in a set or group. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/C/cardinality/#m1)

2) (maths, counting) The idea that the last number you say when counting tells you how many there are in all. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/C/cardinality/#m2)

### sense in the lessons

A maths word: the cardinality of the set {red, blue, green} is 3. In early counting lessons, the «cardinality principle» means the last number counted is the total. Phrases: «the cardinality of a set», «cardinality principle».

### examples

- The cardinality of the set {2, 4, 6, 8} is 4. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/C/cardinality/#x1)
- Count the apples: 1, 2, 3, 4, 5 — the cardinality is 5. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/C/cardinality/#x2)
- Two sets with the same cardinality have the same number of members. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/C/cardinality/#x3)
- The empty set has cardinality 0. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/C/cardinality/#x4)
- What is the cardinality of the set of days in a week? It is 7. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/C/cardinality/#x5)

### note

Technical maths word; in everyday talk say «how many». Related: «cardinal number» (one, two, three — how many) vs «ordinal number» (first, second, third — position). Repeated members count once in a set: {a, a, b} has cardinality 2.

### Trees and pragmatics

[Every meaning and example of «cardinality» parsed by Mova](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/C/cardinality/), each sentence with its dependency tree and frames.