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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Microcontinuity</span></span>
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<p>In <a href="Nonstandard_analysis" title="Nonstandard analysis">nonstandard analysis</a>, a discipline within classical mathematics, <b>microcontinuity</b> (or <i>S</i>-continuity) of an <a href="Internal_function" class="mw-redirect" title="Internal function">internal function</a> <i>f</i> at a point <i>a</i> is defined as follows:
</p>
<dl><dd>for all <i>x</i> infinitely close to <i>a</i>, the value <i>f</i>(<i>x</i>) is infinitely close to <i>f</i>(<i>a</i>).</dd></dl>
<p>Here <i>x</i> runs through the domain of <i>f</i>. In formulas, this can be expressed as follows:
</p>
<dl><dd>if <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle x\approx a}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>x</mi>
<mo>≈<!-- ≈ --></mo>
<mi>a</mi>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle x\approx a}</annotation>
</semantics>
</math></span><img src="./68f8ec36c14cb80f2e78e083d23add919ddfdaa3.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:5.658ex; height:1.676ex;" alt="{\displaystyle x\approx a}" loading="lazy"></span> then <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle f(x)\approx f(a)}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>f</mi>
<mo stretchy="false">(</mo>
<mi>x</mi>
<mo stretchy="false">)</mo>
<mo>≈<!-- ≈ --></mo>
<mi>f</mi>
<mo stretchy="false">(</mo>
<mi>a</mi>
<mo stretchy="false">)</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle f(x)\approx f(a)}</annotation>
</semantics>
</math></span><img src="./deb8b324a1dad075a6639ef9d8e50d50f317c171.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:11.834ex; height:2.843ex;" alt="{\displaystyle f(x)\approx f(a)}" loading="lazy"></span>.</dd></dl>
<p>For a function <i>f</i> defined on <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \mathbb {R} }">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mrow class="MJX-TeXAtom-ORD">
<mi mathvariant="double-struck">R</mi>
</mrow>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle \mathbb {R} }</annotation>
</semantics>
</math></span><img src="./786849c765da7a84dbc3cce43e96aad58a5868dc.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.678ex; height:2.176ex;" alt="{\displaystyle \mathbb {R} }" loading="lazy"></span>, the definition can be expressed in terms of the <a href="Halo_(mathematics)" class="mw-redirect" title="Halo (mathematics)">halo</a> as follows: <i>f</i> is microcontinuous at <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle c\in \mathbb {R} }">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>c</mi>
<mo>∈<!-- ∈ --></mo>
<mrow class="MJX-TeXAtom-ORD">
<mi mathvariant="double-struck">R</mi>
</mrow>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle c\in \mathbb {R} }</annotation>
</semantics>
</math></span><img src="./d47ef490c028656282fd8b18c44c4939bbfff750.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:5.526ex; height:2.176ex;" alt="{\displaystyle c\in \mathbb {R} }" loading="lazy"></span> if and only if <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle f(hal(c))\subseteq hal(f(c))}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>f</mi>
<mo stretchy="false">(</mo>
<mi>h</mi>
<mi>a</mi>
<mi>l</mi>
<mo stretchy="false">(</mo>
<mi>c</mi>
<mo stretchy="false">)</mo>
<mo stretchy="false">)</mo>
<mo>⊆<!-- ⊆ --></mo>
<mi>h</mi>
<mi>a</mi>
<mi>l</mi>
<mo stretchy="false">(</mo>
<mi>f</mi>
<mo stretchy="false">(</mo>
<mi>c</mi>
<mo stretchy="false">)</mo>
<mo stretchy="false">)</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle f(hal(c))\subseteq hal(f(c))}</annotation>
</semantics>
</math></span><img src="./74253a8e2b34ccfc645cbb2d8434ccd682d92786.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:21.431ex; height:2.843ex;" alt="{\displaystyle f(hal(c))\subseteq hal(f(c))}" loading="lazy"></span>, where the natural extension of <i>f</i> to the <a href="Hyperreal_number" title="Hyperreal number">hyperreals</a> is still denoted <i>f</i>. Alternatively, the property of microcontinuity at <i>c</i> can be expressed by stating that the composition <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\text{st}}\circ f}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mrow class="MJX-TeXAtom-ORD">
<mtext>st</mtext>
</mrow>
<mo>∘<!-- ∘ --></mo>
<mi>f</mi>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle {\text{st}}\circ f}</annotation>
</semantics>
</math></span><img src="./538e6c5c4e182b665bdaf369f5619fb606943b2f.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:5.294ex; height:2.509ex;" alt="{\displaystyle {\text{st}}\circ f}" loading="lazy"></span> is constant on the halo of <i>c</i>, where "st" is the <a href="Standard_part_function" title="Standard part function">standard part function</a>.
</p>
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<div class="mw-heading mw-heading2"><h2 id="History">History</h2></div>
<p>The modern property of continuity of a function was first defined by Bolzano in 1817. However, Bolzano's work was not noticed by the larger mathematical community until its rediscovery in Heine in the 1860s. Meanwhile, <a href="Cauchy" class="mw-redirect" title="Cauchy">Cauchy</a>'s textbook <a href="Cours_d'Analyse" class="mw-redirect" title="Cours d'Analyse">Cours d'Analyse</a> defined continuity in 1821 using <a href="Infinitesimal" title="Infinitesimal">infinitesimals</a> as above.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup>
</p>
<div class="mw-heading mw-heading2"><h2 id="Continuity_and_uniform_continuity">Continuity and uniform continuity</h2></div>
<p>The property of microcontinuity is typically applied to the natural extension <i>f*</i> of a real function <i>f</i>. Thus, <i>f</i> defined on a real interval <i>I</i> is <a href="Continuous_function" title="Continuous function">continuous</a> if and only if <i>f*</i> is microcontinuous at every point of <i>I</i>. Meanwhile, <i>f</i> is <a href="Uniformly_continuous" class="mw-redirect" title="Uniformly continuous">uniformly continuous</a> on <i>I</i> if and only if <i>f*</i> is microcontinuous at every point (standard and nonstandard) of the natural extension <i>I*</i> of its domain <i>I</i> (see Davis, 1977, p. 96).
</p>
<div class="mw-heading mw-heading2"><h2 id="Example_1">Example 1</h2></div>
<p>The real function <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle f(x)={\tfrac {1}{x}}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>f</mi>
<mo stretchy="false">(</mo>
<mi>x</mi>
<mo stretchy="false">)</mo>
<mo>=</mo>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="false" scriptlevel="0">
<mfrac>
<mn>1</mn>
<mi>x</mi>
</mfrac>
</mstyle>
</mrow>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle f(x)={\tfrac {1}{x}}}</annotation>
</semantics>
</math></span><img src="./86ad8bb8ae44173f9fc433075758a1750ecf5c51.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:9.292ex; height:3.343ex;" alt="{\displaystyle f(x)={\tfrac {1}{x}}}" loading="lazy"></span> on the open interval (0,1) is not uniformly continuous because the natural extension <i>f*</i> of <i>f</i> fails to be microcontinuous at an <a href="Infinitesimal" title="Infinitesimal">infinitesimal</a> <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle a>0}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>a</mi>
<mo>></mo>
<mn>0</mn>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle a>0}</annotation>
</semantics>
</math></span><img src="./1f34a80ea013edb56e340b19550430a8b6dfd7b9.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:5.491ex; height:2.176ex;" alt="{\displaystyle a>0}" loading="lazy"></span>. Indeed, for such an <i>a</i>, the values <i>a</i> and <i>2a</i> are infinitely close, but the values of <i>f*</i>, namely <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\tfrac {1}{a}}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="false" scriptlevel="0">
<mfrac>
<mn>1</mn>
<mi>a</mi>
</mfrac>
</mstyle>
</mrow>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle {\tfrac {1}{a}}}</annotation>
</semantics>
</math></span><img src="./b01639881379f5c524b620c7bfa4f6d2e2a089ee.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.005ex; width:1.706ex; height:3.343ex;" alt="{\displaystyle {\tfrac {1}{a}}}" loading="lazy"></span> and <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\tfrac {1}{2a}}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="false" scriptlevel="0">
<mfrac>
<mn>1</mn>
<mrow>
<mn>2</mn>
<mi>a</mi>
</mrow>
</mfrac>
</mstyle>
</mrow>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle {\tfrac {1}{2a}}}</annotation>
</semantics>
</math></span><img src="./002715926e86ea3b7011bf1a43cfcebedd5bac08.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.171ex; width:2.528ex; height:3.509ex;" alt="{\displaystyle {\tfrac {1}{2a}}}" loading="lazy"></span> are not infinitely close.
</p>
<div class="mw-heading mw-heading2"><h2 id="Example_2">Example 2</h2></div>
<p>The function <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle f(x)=x^{2}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>f</mi>
<mo stretchy="false">(</mo>
<mi>x</mi>
<mo stretchy="false">)</mo>
<mo>=</mo>
<msup>
<mi>x</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>2</mn>
</mrow>
</msup>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle f(x)=x^{2}}</annotation>
</semantics>
</math></span><img src="./84ddac4ae10b1aa4a11741c79771a583419fb1fb.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:9.9ex; height:3.176ex;" alt="{\displaystyle f(x)=x^{2}}" loading="lazy"></span> on <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \mathbb {R} }">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mrow class="MJX-TeXAtom-ORD">
<mi mathvariant="double-struck">R</mi>
</mrow>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle \mathbb {R} }</annotation>
</semantics>
</math></span><img src="./786849c765da7a84dbc3cce43e96aad58a5868dc.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.678ex; height:2.176ex;" alt="{\displaystyle \mathbb {R} }" loading="lazy"></span> is not uniformly continuous because <i>f*</i> fails to be microcontinuous at an infinite point <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle H\in \mathbb {R} ^{*}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>H</mi>
<mo>∈<!-- ∈ --></mo>
<msup>
<mrow class="MJX-TeXAtom-ORD">
<mi mathvariant="double-struck">R</mi>
</mrow>
<mrow class="MJX-TeXAtom-ORD">
<mo>∗<!-- ∗ --></mo>
</mrow>
</msup>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle H\in \mathbb {R} ^{*}}</annotation>
</semantics>
</math></span><img src="./a492697160190bdf6e11996029748959716debf5.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:7.637ex; height:2.343ex;" alt="{\displaystyle H\in \mathbb {R} ^{*}}" loading="lazy"></span>. Namely, setting <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle e={\tfrac {1}{H}}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>e</mi>
<mo>=</mo>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="false" scriptlevel="0">
<mfrac>
<mn>1</mn>
<mi>H</mi>
</mfrac>
</mstyle>
</mrow>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle e={\tfrac {1}{H}}}</annotation>
</semantics>
</math></span><img src="./6d304549fe6aa8b6e6fa369aeb2957381918a1ca.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -1.171ex; width:6.477ex; height:3.509ex;" alt="{\displaystyle e={\tfrac {1}{H}}}" loading="lazy"></span> and <i>K</i> = <i>H</i> + <i>e</i>, one easily sees that <i>H</i> and <i>K</i> are infinitely close but <i>f</i>*(<i>H</i>) and <i>f</i>*(<i>K</i>) are not infinitely close.
</p>
<div class="mw-heading mw-heading2"><h2 id="Uniform_convergence">Uniform convergence</h2></div>
<p><a href="Uniform_convergence" title="Uniform convergence">Uniform convergence</a> similarly admits a simplified definition in a hyperreal setting. Thus, a sequence <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle f_{n}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<msub>
<mi>f</mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>n</mi>
</mrow>
</msub>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle f_{n}}</annotation>
</semantics>
</math></span><img src="./b2702450f0458a5e01a698e248af552a7fab2b50.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.358ex; height:2.509ex;" alt="{\displaystyle f_{n}}" loading="lazy"></span> converges to <i>f</i> uniformly if for all <i>x</i> in the domain of <i>f*</i> and all infinite <i>n</i>, <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle f_{n}^{*}(x)}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<msubsup>
<mi>f</mi>
<mrow class="MJX-TeXAtom-ORD">
<mi>n</mi>
</mrow>
<mrow class="MJX-TeXAtom-ORD">
<mo>∗<!-- ∗ --></mo>
</mrow>
</msubsup>
<mo stretchy="false">(</mo>
<mi>x</mi>
<mo stretchy="false">)</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle f_{n}^{*}(x)}</annotation>
</semantics>
</math></span><img src="./5f3512b1338c39b83752a58ede045cf60cb50c78.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:5.514ex; height:2.843ex;" alt="{\displaystyle f_{n}^{*}(x)}" loading="lazy"></span> is infinitely close to <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle f^{*}(x)}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<msup>
<mi>f</mi>
<mrow class="MJX-TeXAtom-ORD">
<mo>∗<!-- ∗ --></mo>
</mrow>
</msup>
<mo stretchy="false">(</mo>
<mi>x</mi>
<mo stretchy="false">)</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle f^{*}(x)}</annotation>
</semantics>
</math></span><img src="./b6b4088f786acb68c65dda1da1bfd5b022023c3e.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:5.514ex; height:2.843ex;" alt="{\displaystyle f^{*}(x)}" loading="lazy"></span>.
</p>
<div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2></div>
<ul><li><a href="Standard_part_function" title="Standard part function">Standard part function</a></li></ul>
<div class="mw-heading mw-heading2"><h2 id="Bibliography">Bibliography</h2></div>
<ul><li><a href="Martin_Davis_(mathematician)" title="Martin Davis (mathematician)">Martin Davis</a> (1977) Applied nonstandard analysis. Pure and Applied Mathematics. Wiley-Interscience [John Wiley & Sons], New York-London-Sydney. xii+181 pp. <style data-mw-deduplicate="TemplateStyles:r1238218222">
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</style><a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>0-471-19897-8</bdi></li>
<li>Gordon, E. I.; Kusraev, A. G.; <a href="Semen_Samsonovich_Kutateladze" class="mw-redirect" title="Semen Samsonovich Kutateladze">Kutateladze</a>, S. S.: Infinitesimal analysis. Updated and revised translation of the 2001 Russian original. Translated by Kutateladze. Mathematics and its Applications, 544. Kluwer Academic Publishers, Dordrecht, 2002.</li></ul>
<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>
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<div class="mw-references-wrap"><ol class="references">
<li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><cite id="CITEREFBorovikKatz2011" class="citation cs2"><a href="Alexandre_Borovik" title="Alexandre Borovik">Borovik, Alexandre</a>; <a href="Mikhail_Katz" title="Mikhail Katz">Katz, Mikhail G.</a> (2011), "Who gave you the Cauchy--Weierstrass tale? The dual history of rigorous calculus", <i><a href="Foundations_of_Science" title="Foundations of Science">Foundations of Science</a></i>, <b>17</b> (3): <span class="nowrap">245–</span>276, <a href="ArXiv_(identifier)" class="mw-redirect" title="ArXiv (identifier)">arXiv</a>:<span class="id-lock-free" title="Freely accessible"><a rel="nofollow" class="external text" href="https://arxiv.org/abs/1108.2885">1108.2885</a></span>, <a href="Doi_(identifier)" class="mw-redirect" title="Doi (identifier)">doi</a>:<a rel="nofollow" class="external text" href="https://doi.org/10.1007%2Fs10699-011-9235-x">10.1007/s10699-011-9235-x</a></cite>.</span>
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</style><div id="Infinitesimals97" style="font-size:114%;margin:0 4em"><a href="Infinitesimal" title="Infinitesimal">Infinitesimals</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">History</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">
<ul><li><a href="Adequality" title="Adequality">Adequality</a></li>
<li><a href="Leibniz's_notation" title="Leibniz's notation">Leibniz's notation</a></li>
<li><a href="Integral_symbol" title="Integral symbol">Integral symbol</a></li>
<li><a href="Criticism_of_nonstandard_analysis" title="Criticism of nonstandard analysis">Criticism of nonstandard analysis</a></li>
<li><i><a href="The_Analyst" title="The Analyst">The Analyst</a></i></li>
<li><i><a href="The_Method_of_Mechanical_Theorems" title="The Method of Mechanical Theorems">The Method of Mechanical Theorems</a></i></li>
<li><a href="Cavalieri's_principle" title="Cavalieri's principle">Cavalieri's principle</a></li></ul>
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<ul><li><a href="Nonstandard_analysis" title="Nonstandard analysis">Nonstandard analysis</a></li>
<li><a href="Nonstandard_calculus" title="Nonstandard calculus">Nonstandard calculus</a></li>
<li><a href="Internal_set_theory" title="Internal set theory">Internal set theory</a></li>
<li><a href="Synthetic_differential_geometry" title="Synthetic differential geometry">Synthetic differential geometry</a></li>
<li><a href="Smooth_infinitesimal_analysis" title="Smooth infinitesimal analysis">Smooth infinitesimal analysis</a></li>
<li><a href="Constructive_nonstandard_analysis" title="Constructive nonstandard analysis">Constructive nonstandard analysis</a></li>
<li><a href="Infinitesimal_strain_theory" title="Infinitesimal strain theory">Infinitesimal strain theory (physics)</a></li></ul>
</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Formalizations</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">
<ul><li><a href="Differential_(mathematics)" title="Differential (mathematics)">Differentials</a></li>
<li><a href="Hyperreal_number" title="Hyperreal number">Hyperreal numbers</a></li>
<li><a href="Dual_number" title="Dual number">Dual numbers</a></li>
<li><a href="Surreal_number" title="Surreal number">Surreal numbers</a></li></ul>
</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Individual concepts</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">
<ul><li><a href="Standard_part_function" title="Standard part function">Standard part function</a></li>
<li><a href="Transfer_principle" title="Transfer principle">Transfer principle</a></li>
<li><a href="Hyperinteger" title="Hyperinteger">Hyperinteger</a></li>
<li><a href="Increment_theorem" title="Increment theorem">Increment theorem</a></li>
<li><a href="Monad_(nonstandard_analysis)" title="Monad (nonstandard analysis)">Monad</a></li>
<li><a href="Internal_set" title="Internal set">Internal set</a></li>
<li><a href="Levi-Civita_field" title="Levi-Civita field">Levi-Civita field</a></li>
<li><a href="Hyperfinite_set" title="Hyperfinite set">Hyperfinite set</a></li>
<li><a href="Law_of_continuity" title="Law of continuity">Law of continuity</a></li>
<li><a href="Overspill" title="Overspill">Overspill</a></li>
<li><a href="Transcendental_law_of_homogeneity" title="Transcendental law of homogeneity">Transcendental law of homogeneity</a></li></ul>
</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Mathematicians</th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">
<ul><li><a href="Gottfried_Wilhelm_Leibniz" title="Gottfried Wilhelm Leibniz">Gottfried Wilhelm Leibniz</a></li>
<li><a href="Abraham_Robinson" title="Abraham Robinson">Abraham Robinson</a></li>
<li><a href="Pierre_de_Fermat" title="Pierre de Fermat">Pierre de Fermat</a></li>
<li><a href="Augustin-Louis_Cauchy" title="Augustin-Louis Cauchy">Augustin-Louis Cauchy</a></li>
<li><a href="Leonhard_Euler" title="Leonhard Euler">Leonhard Euler</a></li></ul>
</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Textbooks</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0;font-style:italic;"><div style="padding:0 0.25em">
<ul><li><a href="Analyse_des_Infiniment_Petits_pour_l'Intelligence_des_Lignes_Courbes" class="mw-redirect" title="Analyse des Infiniment Petits pour l'Intelligence des Lignes Courbes">Analyse des Infiniment Petits</a></li>
<li><a href="Elementary_Calculus%3A_An_Infinitesimal_Approach" title="Elementary Calculus: An Infinitesimal Approach">Elementary Calculus</a></li>
<li><a href="Cours_d'analyse" title="Cours d'analyse">Cours d'analyse</a></li></ul>
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