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Does there exist a mathematical term to refer to the number of unique elements in a multiset/sequence/tuple? For example, if a tuple $T$ is $[2, 4, 2, 10, 4, 8, 10]$, then the number of unique elements in $T$ is $4$: $$[2, 4, 8, 10].$$ The term “cardinality” is not suitable because, according to Wikipedia, if $M = \{a, a, b, b, b, c\}$ is a multiset, then its cardinality is $6$, although the number of unique elements in $M$ is $3$:$$\{a, b, c\}.$$

lyrically wicked
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  • I'd likely just call it the 'number of distinct elements', or perhaps the 'cardinality of the range'. – Hayden Nov 24 '18 at 09:03

1 Answers1

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I have found that the term “dimension” may be suitable here (source):

The root set (or support set) of a multiset is the set of its distinct elements. The dimension of a multiset is the cardinality of the support set.

lyrically wicked
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