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 | A val is more specific than a [[mapping]]: | ||
# A val | # 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]]. |