Val: Difference between revisions

Cmloegcmluin (talk | contribs)
Vals vs. mappings: clarify a confusing consecutive usage of two different senses of "mapping" (general mathematical vs. RTT)
Cmloegcmluin (talk | contribs)
Vals vs. mappings: adjust further re: thoughts from Dave
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== Vals vs. mappings ==
== Vals vs. mappings ==


A val is more specific than a mapping, both as in the general mathematical sense as well as [[mapping|the regular temperament sense]]:
A val is more specific than a [[mapping]]:
# A val can be thought of as a mapping (in the general mathematical sense) with one row. Put another way, the rows of mappings (in the regular temperament sense) are vals. To be mathematically precise, a val is a specific type of [[Wikipedia:Linear_map|(linear) mapping]] called a [[Wikipedia:Linear_form|"linear form", or "linear functional"]], which means that its output is a [[Wikipedia:Scalar_(mathematics)|scalar]], or in other words, a single number. This corresponds to the fact that a val must be a 1xM array of numbers, or in other words a [[Wikipedia:Vector_(mathematics_and_physics)|vector]] (specifically a [[Wikipedia:Row_and_column_vectors|row vector]], AKA covector).
# A val is either a single row of a mapping, or a mapping with a single row. To be mathematically precise, a val is a specific type of [[Wikipedia:Linear_map|''linear'' function]] (which is also called a "linear mapping" or "linear map", because in general mathematics, "function", "mapping", and "map" are synonymous) called a [[Wikipedia:Linear_form|"linear form", or "linear functional"]], which means that its output is a [[Wikipedia:Scalar_(mathematics)|scalar]], or in other words, a single number. This corresponds to the fact that a val must be a 1xM array of numbers, or in other words a [[Wikipedia:Vector_(mathematics_and_physics)|vector]] (specifically a [[Wikipedia:Row_and_column_vectors|row vector]], AKA covector).
# Vals must have only integer entries (when expressed in the standard, non-weighted coordinate basis).
# Vals must have only integer entries (when expressed in the standard, non-weighted coordinate basis).
# Being short for "[[Wikipedia:Valuation_(algebra)|valuation]]", a val is a formal linear sum of [[Wikipedia:P-adic_order|p-adic valuations]].
# Being short for "[[Wikipedia:Valuation_(algebra)|valuation]]", a val is a formal linear sum of [[Wikipedia:P-adic_order|p-adic valuations]].
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