Blackboard bold

Blackboard bold
"Doublestrike" redirects here. For other uses, see Double Strike (disambiguation).
An example of blackboard bold letters.

Blackboard bold is a typeface style that is often used for certain symbols in mathematical texts, in which certain lines of the symbol (usually vertical or near-vertical lines) are doubled. The symbols usually denote number sets. Blackboard bold symbols are also referred to as double struck, although they cannot actually be produced by double striking on a typewriter.

In some texts these symbols are simply shown in bold type: blackboard bold in fact originated from the attempt to write bold letters on blackboards in a way that clearly differentiated them from non-bold letters, and then made its way back in print form as a separate style from ordinary bold,[1] possibly starting with the original 1965 edition of Gunning and Rossi's textbook on complex analysis.[2] Some mathematicians, therefore, do not recognize blackboard bold as a separate style from bold: Jean-Pierre Serre, for example, has publicly inveighed against the use of "blackboard bold" anywhere other than on a blackboard,[citation needed] and uses double-struck letters when writing bold on the blackboard,[3] whereas his published works consistently use ordinary bold for the same symbols.[4] It is sometimes erroneously claimed[1] that Bourbaki introduced the blackboard bold notation, but whereas individual members of the Bourbaki group may have popularized double-striking bold characters on the blackboard, their printed books use ordinary bold.[5]

The symbols are nearly universal in their interpretation, unlike their normally-typeset counterparts, which are used for many different purposes.

TeX, the standard typesetting system for mathematical texts, does not contain direct support for blackboard bold symbols, but the add-on AMS Fonts package (amsfonts) by the American Mathematical Society provides this facility; a blackboard bold R is written as \mathbb{R}.

In Unicode, a few of the more common blackboard bold characters (C, H, N, P, Q, R and Z) are encoded in the Basic Multilingual Plane (BMP) in the Letterlike Symbols (2100–214F) area, named DOUBLE-STRUCK CAPITAL C etc. The rest, however, are encoded outside the BMP, from U+1D538 to U+1D550 (uppercase, excluding those encoded in the BMP), U+1D552 to U+1D56B (lowercase) and U+1D7D8 to U+1D7E1 (digits). Being outside the BMP, these are relatively new and not widely supported.

Contents

Examples

The following table shows all available Unicode blackboard bold characters.

The first column shows the letter as typically rendered by the ubiquitous LaTeX markup system. The second column shows the Unicode codepoint. The third column shows the symbol itself (which will only display correctly if your browser supports Unicode and has access to a suitable font). The fourth column describes known typical (but not universal) usage in mathematical texts.

\LaTeX Unicode (Hex) Symbol Mathematics usage
\mathbb{A} U+1D538

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • blackboard bold — noun A typeface used for representing bold characters, mainly used in mathematical texts, that allows these characters to be easily distinguished from non bold characters when written …   Wiktionary

  • Blackboard — The word Blackboard may refer to:* Chalkboard, a reusable writing surface * Blackboard system, an area of shared memory, or workspace, in Computer Science * Blackboard Inc., an e learning software company * Blackboard bold, a style of typeface… …   Wikipedia

  • Gary E. J. Bold — Gary E.J. Bold, a New Zealand physicist and educator, the introduction of Bold s Equation has become extremely beneficiary to thousands of New Zealand physics graduates over decades. Bold is an Honorary Associate Professor in physics at the… …   Wikipedia

  • Wikipedia:Manual of Style/Mathematics — This guideline is a part of the English Wikipedia s Manual of Style. Use common sense in applying it; it will have occasional exceptions. Please ensure that any edits to this page reflect consensus. Shortcuts: WP:MSM MO …   Wikipedia

  • Naive set theory — This article is about the mathematical topic. For the book of the same name, see Naive Set Theory (book). Naive set theory is one of several theories of sets used in the discussion of the foundations of mathematics.[1] The informal content of… …   Wikipedia

  • Typographical conventions in mathematical formulae — provide uniformity across mathematical texts and help the readers of those texts to grasp new concepts quickly.Mathematical notation includes letters from various alphabets, as well as special mathematical symbols. Letters in various fonts often… …   Wikipedia

  • MathTime — MathTime[1] (sometimes MathTıme) is a commercial set of Times compatible mathematical type family for TeX, created by Michael Spivak. Used together with Times, it is one of the few typefaces that provide full featured text and mathematical… …   Wikipedia

  • Usando TeX — Ayuda:Usando TeX Saltar a navegación, búsqueda TeX. Atajos …   Wikipedia Español

  • Ayuda:Usando TeX — TeX. Atajos A:UTX …   Wikipedia Español

  • Set (mathematics) — This article gives an introduction to what mathematicians call intuitive or naive set theory; for a more detailed account see Naive set theory. For a rigorous modern axiomatic treatment of sets, see Set theory. The intersection of two sets is… …   Wikipedia

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”