Talk:Dual system

Changes as of 18th Feb 21

@Quondum: Especially, if $K\in \{\mathbb {R} ,\mathbb {C} \}$ we denote it by $\mathbb {K}$ or $\mathbb {k}$ or $𝕂$ , so that we notice that it is NOT a variable. –Nomen4Omen (talk) 19:17, 18 February 2021 (UTC)[reply]

Perhaps not the kind of variable as most people think of it, but here it is a variable that takes values that are sets (or fields). There are numerous articles in mathematics in WP that denote an unspecified field as

K

or

F

, for example the articles Field (mathematics), Finite field, Algebra over a field, Vector space, Matrix (mathematics) § Matrices with more general entries, Exterior algebra. —Quondum 20:14, 18 February 2021 (UTC)[reply]

Is black-board K a neologism of some kind? I can see why it is appealing, but I've never seen in any math book I've ever read, nor have I seen it in Wikipedia, up until today. 67.198.37.16 (talk) 05:09, 26 November 2023 (UTC)[reply]