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<h1><a name="intro" id="intro"></a>1 Introduction
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<!-- TOP NAVIGATION BAR -->
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<div class="minitoc">
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Overview: <a href="Overview-d.html">Mathematical Markup Language (MathML) Version 3.0</a><br>
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Next: 2 <a href="chapter2-d.html">MathML Fundamentals</a><br><br>1 <a href="chapter1-d.html">Introduction</a><br> 1.1 <a href="chapter1-d.html#intro.notation">Mathematics and its Notation</a><br> 1.2 <a href="chapter1-d.html#intro.origin">Origins and Goals</a><br> 1.2.1 <a href="chapter1-d.html#intro.goals">Design Goals of MathML</a><br> 1.3 <a href="chapter1-d.html#intro.overview">Overview</a><br> 1.4 <a href="chapter1-d.html#intro.example">A First Example</a><br></div>
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<h2><a name="intro.notation" id="intro.notation"></a>1.1 Mathematics and its Notation
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<p>A distinguishing feature of mathematics is the use of a complex and
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highly evolved system of two-dimensional symbolic notation. As
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J. R. Pierce writes in his book on communication theory,
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mathematics and its notation should not be viewed as one and the same
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thing <a href="appendixh-d.html#Pierce1961">[Pierce1961]</a>. Mathematical ideas can exist independently of
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the notation that represents them. However, the relation between meaning
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and notation is subtle, and part of the power of mathematics to describe
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and analyze derives from its ability to represent and manipulate ideas in
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symbolic form. The challenge before a Mathematical Markup Language (MathML)
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in enabling mathematics on the World Wide Web
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is to capture both notation and content (that is, its meaning) in such a way
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that documents can utilize the highly evolved notation of written
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and printed mathematics as well as the new potential for interconnectivity in
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<p>Mathematical notation evolves constantly as people continue
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to innovate in ways of approaching and expressing ideas. Even
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the common notation of arithmetic has gone through an amazing
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variety of styles, including many defunct ones advocated by leading
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mathematical figures of their day <a href="appendixh-d.html#Cajori1928">[Cajori1928]</a>. Modern
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mathematical notation is the product of centuries of refinement, and
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the notational conventions for high-quality typesetting are quite
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complicated and subtle. For example, variables and letters which stand for
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numbers are usually typeset today in a special mathematical italic
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font subtly distinct from the usual text italic; this seems to have been
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introduced in Europe in the late sixteenth century. Spacing around
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symbols for operations such as +, -, × and / is slightly
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different from that of text, to reflect conventions about operator
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precedence that have evolved over centuries.
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Entire books have been devoted to the conventions of
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mathematical typesetting, from the alignment of superscripts and
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subscripts, to rules for choosing parenthesis sizes, and on to
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specialized notational practices for subfields of mathematics. The
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manuals describing the nuances of present-day computer typesetting and
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composition systems can run to hundreds of pages.
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<p>Notational conventions in mathematics, and in printed text in general,
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guide the eye and make printed expressions much easier to read and
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understand. Though we usually take them for granted, we, as modern readers,
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numerous conventions such as paragraphs, capital letters, font
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families and cases, and even the device of decimal-like numbering of
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sections such as is used in this document.
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Such notational conventions are perhaps even more important
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for electronic media, where one must contend with the difficulties of
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on-screen reading. Appropriate standards coupled with computers
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enable a broadening of access to mathematics beyond the world of
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print. The markup methods for mathematics in use
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just before the Web rose to prominence importantly included T<sub>E</sub>X
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(also written <code>TeX</code>) <a href="appendixh-d.html#Knuth1986">[Knuth1986]</a>
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and approaches based on SGML (<a href="appendixh-d.html#AAP-math">[AAP-math]</a>, <a href="appendixh-d.html#Poppelier1992">[Poppelier1992]</a> and <a href="appendixh-d.html#ISO-12083">[ISO-12083]</a>).
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<p>It is remarkable how widespread the current
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conventions of mathematical notation have become. The general
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two-dimensional layout, and most of the same symbols, are used
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in all modern mathematical communications,
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whether the participants are, say, European, writing left-to-right,
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or Middle-Eastern, writing right-to-left. Of course, conventions
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for the symbols used, particularly those naming functions and
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variables, may tend to favor a local language and script.
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The largest variation from the most common is a form used in
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some Arabic-speaking communities which lays out the entire
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mathematical notation from right-to-left, roughly in mirror image
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of the European tradition.
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<p>However, there is more to putting mathematics on the Web
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than merely finding ways of displaying traditional
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mathematical notation in a Web browser. The Web represents a
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fundamental change in the underlying metaphor for knowledge
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storage, a change in which <em>interconnection</em>
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plays a central role. It has become important to
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find ways of communicating mathematics which facilitate
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automatic processing, searching and indexing, and reuse in
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other mathematical applications and contexts. With this
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advance in communication technology, there is an opportunity
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to expand our ability to represent, encode, and ultimately to
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communicate our mathematical insights and understanding with
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each other. We believe that MathML as specified below is an important step in
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developing mathematics on the Web.
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<h2><a name="intro.origin" id="intro.origin"></a>1.2 Origins and Goals
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<h3><a name="intro.goals" id="intro.goals"></a>1.2.1 Design Goals of MathML
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<p>MathML has been designed from the beginning with the following
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ultimate goals in mind.
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<p>MathML should ideally:
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<p>Encode mathematical material suitable for all educational
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and scientific communication.
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<p>Encode both mathematical notation and mathematical meaning.</p>
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<p>Facilitate conversion to and from other mathematical
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formats, both presentational and semantic. Output formats should include:
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<p>graphical displays</p>
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<p>speech synthesizers</p>
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<p>input for computer algebra systems</p>
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<p>other mathematics typesetting languages, such as T<sub>E</sub>X
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<p>plain text displays, e.g. VT100 emulators</p>
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<p>international print media, including braille</p>
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<p>It is recognized that conversion to and from other notational
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systems or media may entail loss of information in the process.
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<p>Allow the passing of information intended for
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specific renderers and applications.
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<p>Support efficient browsing of lengthy expressions.</p>
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<p>Provide for extensibility.</p>
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<p>Be well suited to templates and other common techniques for editing formulas.</p>
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<p>Be legible to humans, and simple for software to generate and process.</p>
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<p>No matter how successfully MathML achieves its goals as
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a markup language, it is clear that MathML is useful only
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if it is implemented well. The W3C Math Working
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Group has identified a short list of additional implementation
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goals. These goals attempt to describe concisely the minimal
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functionality MathML rendering and processing software should
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<p>MathML expressions in HTML (and XHTML) pages should render
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properly in popular Web browsers, in accordance with reader and author
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viewing preferences, and at the highest quality possible given the
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capabilities of the platform.
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<p>HTML (and XHTML) documents containing MathML expressions should
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print properly and at high-quality printer resolutions.
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<p>MathML expressions in Web pages should be able to react to
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user gestures, such those as with a mouse, and to coordinate
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communication with other applications through the
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<p>Mathematical expression editors and converters should be developed
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to facilitate the creation of Web pages containing MathML
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<p>The extent to which these goals are ultimately met depends on the
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cooperation and support of browser vendors and other developers. The W3C
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Math Working Group has continued to work with other working groups of the W3C,
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and outside the W3C, to ensure that the
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needs of the scientific community will be met.
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MathML 2 and its implementations showed considerable progress in this area
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over the situation that obtained at
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the time of the MathML 1.0 Recommendation (April 1998) <a href="appendixh-d.html#MathML1">[MathML1]</a>. MathML3 and the developing Web are expected to
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<h2><a name="intro.overview" id="intro.overview"></a>1.3 Overview
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<p>MathML is designed as an `XML Application', that is,
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it uses XML markup for describing mathematics.
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A special aspect of MathML is that there are two main strains of markup:
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Presentation markup, discussed in <a href="chapter3-d.html">Chapter 3 Presentation Markup</a>,
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is used to display mathematical expressions;
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and Content markup, discussed in <a href="chapter4-d.html">Chapter 4 Content Markup</a>,
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is used to convey mathematical meaning.
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Content markup is specified in particular detail.
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This specification makes use of a format called Content Dictionaries,
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which is also an application of XML.
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This format has been developed by the
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OpenMath Society, <a href="appendixg-d.html#OpenMath2004">[OpenMath2004]</a> with the dictionaries being used by this specification involving joint development by the OpenMath Society and the W3C Math
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<p>Fundamentals common to both strains of markup
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are covered in <a href="chapter2-d.html">Chapter 2 MathML Fundamentals</a>,
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while the means for combining these strains,
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as well as external markup, into single MathML objects
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are discussed in <a href="chapter5-d.html">Chapter 5 Mixing Markup Languages for Mathematical Expressions</a>.
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How MathML interacts with applications is covered
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in <a href="chapter6-d.html">Chapter 6 Interactions with the Host Environment</a>.
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Finally, a discussion of special symbols,
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and issues regarding characters, entities and fonts,
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is given in <a href="chapter7-d.html">Chapter 7 Characters, Entities and Fonts</a>.
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<h2><a name="intro.example" id="intro.example"></a>1.4 A First Example
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The quadratic formula provides a
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simple but instructive illustration of MathML markup.
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<p><img src="image/f1002.gif" alt="x = \frac{-b\pm\sqrt{b^2 - 4ac}}{2a}"></p>
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<p>MathML offers two flavors of markup of this formula. The first is
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the style which emphasizes the actual presentation of a formula, the
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two-dimensional layout in which the symbols are arranged. An example
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of this type is given just below. The second flavor
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emphasizes the mathematical content and an example of it follows the first one.
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</p><pre class="mathml">
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<mi>x</mi>
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<mo>=</mo>
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<mo>-</mo>
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<mi>b</mi>
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<mo>&#xB1;<span style="color:#999900"><!--PLUS-MINUS SIGN--></span></mo>
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<mi>b</mi>
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<mn>2</mn>
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<mo>-</mo>
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<mn>4</mn>
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<mo>&#x2062;<span style="color:#999900"><!--INVISIBLE TIMES--></span></mo>
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<mi>a</mi>
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<mo>&#x2062;<span style="color:#999900"><!--INVISIBLE TIMES--></span></mo>
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<mi>c</mi>
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<mn>2</mn>
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<mo>&#x2062;<span style="color:#999900"><!--INVISIBLE TIMES--></span></mo>
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<mi>a</mi>
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Consider the superscript 2 in this formula. It represents the squaring operation
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here, but the meaning of a superscript in other situations depends on
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the context. A letter with a superscript can be used to signify a particular
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component of a vector, or maybe the superscript just labels a different
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type of some structure. Similarly two letters written one just after the
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other could signify two variables multiplied together, as they do in the
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quadratic formula, or they could be two letters making up the name of a
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single variable. What is called Content Markup in MathML allows closer
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specification of the mathematical meaning of many common formulas. The
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quadratic formula given in this style of markup is as follows.
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</p><pre class="mathml">
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<ci>x</ci>
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<ci>b</ci>
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<ci>b</ci>
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<cn>2</cn>
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<cn>4</cn>
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<ci>a</ci>
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<ci>c</ci>
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<cn>2</cn>
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<ci>a</ci>
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<div class="minitoc">
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Overview: <a href="Overview-d.html">Mathematical Markup Language (MathML) Version 3.0</a><br>
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Next: 2 <a href="chapter2-d.html">MathML Fundamentals</a></div>
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