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% This is the sample paper for the AmSTeX SIAM style file, (amstex)siam.sty
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% for use with AmSTeX version 2.1 or later and amsppt.sty, version 2.1a.
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% RCS information: $Revision: 1.1 $, $Date: 93/01/25 15:33:19 $.
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\documentstyle{amstexs1}
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% Macro definitions for running heads and first page %
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\issuemonth{February} %
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\placenumber{002} % place of paper in this issue %
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\shortauthor{Bradley J. Lucier and Douglas N. Arnold} %
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\shorttitle{A Sample Paper} %
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% Macros specific to this paper %
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\define\loner{{L^1(\Bbb R)}} %
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\define\linfr{{L^\infty(\Bbb R)}} %
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\define\bvr{{\roman{BV}(\Bbb R)}} %
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\define\TV{{\roman {TV}}} %
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\define\sdot{\,\cdot\,} %
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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A SAMPLE PAPER, WITH A RATHER LONG TITLE, TO ILLUSTRATE THE
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\AmSTeX\ SIAM STYLE\footnote[\boldkey*]{Unlikely to appear.}
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BRADLEY J. LUCIER\footnote[\dag]{Department of Mathematics, Purdue University,
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West Lafayette, Indiana 47907. Present address, somewhere on the beach
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(lucier\@math.purdue.edu).
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The work of the first author was not supported by the
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Wolf Foundation.}\ and DOUGLAS N. ARNOLD\footnote[\ddag]{Department
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of Mathematics, Pennsylvania State University,
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University Park, Pennsylvania 16802.}
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This sample paper illustrates many of the amstex
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macros as used with the \AmSTeX\ SIAM style file amstexsiam (version 2.0a).
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The \AmSTeX\ SIAM style file, which
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inputs and builds upon the amsppt style (version 2.1a or later)
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of Michael Spivak, gives authors easy
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access to most of the typographical constructions used in SIAM journals.
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It does not address the issues of the table of contents
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or tables, which must be set using more primitive \TeX\ macros.
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porous medium, interface curves
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\subhead 1. Introduction\endsubhead
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We are concerned with numerical approximations to the so-called
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porous-medium equation \cite{6},
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&u_t=\phi(u)_{xx},&&\qquad x\in\Bbb R,\quad t>0,\quad\phi(u)=u^m,\quad m>1,
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&u(x,0)=u_0(x),&&\qquad x\in\Bbb R.
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We assume that the initial data $u_0(x)$ has bounded support, that
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$0\leq u_0\leq M$, and that $\phi(u_0)_x\in\bvr$.
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It is well known that a unique solution $u(x,t)$ of (1.1) exists,
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and that $u$ satisfies
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0\leq u\leq M\text{ and }\TV\phi(u(\,\cdot\,,t))_x\leq\TV\phi(u_0)_x.
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If the data has slightly more regularity, then this too is satisfied
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by the solution. Specifically, if $m$ is no greater than two and
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$u_0$ is Lipschitz continuous, then $u(\,\cdot\,,t)$ is also Lipschitz;
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if $m$ is greater than two and $(u_0^{m-1})_x\in\linfr$, then
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$(u(\,\cdot\,,t)^{m-1})_x\in\linfr$
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(see [3]). (This will follow from results presented here, also.)
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We also use the fact that the solution $u$ is H\"older continuous in $t$.
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\subhead 2. $\linfr$ error bounds\endsubhead
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After a simple definition, we state a theorem
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that expresses the error of approximations $u^h$ in
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terms of the weak truncation error $E$.
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\definition{Definition 2.1}\rm A {\it definition}
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is the same as a theorem set in roman
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type. In version 2 of the \AmSTeX\ style file for the SIAM journals,
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definitions are set with their own command.
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\proclaim{Theorem 2.1}
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Let $\{u^h\}$ be a family of approximate solutions satisfying
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the following conditions for $0\leq t\leq T${\rm:}
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\item For all $x\in\Bbb R$ and positive $t$, $0\leq u^h(x,t)\leq M${\rm;}
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\item Both $u$ and $u^h$ are H\"older--$\alpha$ in $x$
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for some $\alpha\in(0,1\wedge 1/(m-1))${\rm;} $u^h$ is right
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continuous in $t${\rm;}
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and $u^h$ is H\"older continuous in $t$ on
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strips $\Bbb R\times(t^n,t^{n+1})$, with the set $\{t^n\}$ having no
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limit points\/{\rm;} and
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\item There exists a positive function $\omega(h,\epsilon)$ such that\/{\rm:}
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whenever $\{w^\epsilon\}_{0<\epsilon\leq\epsilon_0}$ is a family of functions
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in $\bold X$ for which
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\item"(a)" there is a sequence of positive numbers $\epsilon$ tending
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to zero, such that for these values of
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$\epsilon$, $\|w^\epsilon\|_\infty\leq 1/\epsilon$,
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\item"(b)" for all positive
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$\epsilon$, $\|w_x^\epsilon(\sdot,t)\|_\loner\leq 1/\epsilon^2$, and
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\item"(c)" for all $\epsilon>0$,
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x\in\Bbb R\\0\leq t_1,t_2\leq T\endSb
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\dfrac{|w^\epsilon(x,t_2)-w^\epsilon(x,t_1)|}{|t_2-t_1|^p}\leq 1/\epsilon^2,
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where $p$ is some number not exceeding $1$,
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then\footnote{This is an obvious ploy, but we need a footnote.}
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$|E (u^h,w^\epsilon,T)|\leq\omega(h,\epsilon).$
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This is the fourth item in the outer roster.
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Then, there is a constant $C=C(m,M,T)$ such that
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\|u-u^h\|_{\infty,\Bbb R\times[0,T]}\leq C\biggl[
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\sup \biggl |\int_\Bbb R(u_0(x)-u^h(x,0)) w(x,0) \,dx\biggr|\\
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+\omega(h,\epsilon)+\epsilon^\alpha\biggr],\endmultline
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where the supremum is taken over all $w\in\bold X$.
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We assume first that $Q$ is decreasing and consider the following cases:
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$b'\geq 1/2$} We have $P(1/8)\geq\delta>0$ where $\delta$
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depends only on $d$, for otherwise by (3.7) applied to $P$ and $p=\infty$,
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$P$ could not attain the value $1$ at $x=1$. Similarly, for
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$m=(a'+b')/2$, $Q(m)\geq\delta'>0$ for some $\delta'$ depending only on $d$
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since otherwise $Q$ cannot attain the value $1$ at $x=a'$. Hence, for
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$\delta''=\min(\delta,\delta')$,
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$|A(y)|\geq|m-1/8|\geq b'/4\geq\frac18\max(b',1)$ for
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$y\in[0,\delta'']$. On the other hand,
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$|A(y)|\leq \max(b',1)$ for all $y\in[0,1]$, so (4.2) follows for
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all $1\leq p\leq\infty$.
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$b'\leq 1/2$} We have $P(3/4)\leq\delta<1$ with $\delta$
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depending only on $d$ for otherwise (3.7) applied to $1-P$ and $p=\infty$
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would show that $P$ could not attain the value $0$ at $x=0$. It follows
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that $|A(y)|\geq 3/4-b'\geq 1/4$, $y\in[\delta,1]$, while $|A(y)|\leq 1$
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for all $y\in[0,1]$. Hence (4.2) follows for
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all $1\leq p\leq\infty$.
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We consider now when $Q$ is increasing. We can assume that $Q$ is not
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a translate of $P$, i.e\., we do not have $P(x)=Q(x+\delta)$ for some $\delta$,
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for then (4.2) follows trivially. In what follows, $C$ and $\delta$
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depend on $d$, and $C$ may depend on $p$. We consider the following cases:
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\case{Case\/ {\rm3:} $a'\geq 1/4$ and $b'\leq 100$}
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and $p=\infty$, it follows that $P(1/8)\geq\delta$ since otherwise $P$ cannot
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attain the value $1$ at $x=1$. Hence $|A(y)|\geq a'-1/8\geq1/8$ on
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$[0,\delta]$. On the other hand $|A(y)|\leq b'$ for all $y\in[0,1]$ and hence
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(4.2) follows for all $1\leq p\leq\infty$.
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Let $z$ be in $\bold X$. Because $E(u,\sdot,\sdot)\equiv0$,
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Equation (1.5) implies that
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\int_\Bbb R\Delta uz|^T_0dx=\int_0^T\int_\Bbb R
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\Delta u(z_t+\phi[u,u^h]z_{xx})\,dx\,dt-
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where $\Delta u=u-u^h$ and
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\phi[u,u^h]=\dfrac{\phi(u)-\phi(u^h)}{u-u^h}.
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Extend $\phi[u,u^h](\cdot,t)=\phi[u,u^h](\cdot,0)$ for negative $t$, and
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$\phi[u,u^h](\cdot,t)=\phi[u,u^h](\cdot,T)$
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Fix a point $x_0$ and a number $\epsilon>0$. Let $j_\epsilon$
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be a smooth function of $x$ with integral $1$ and support in
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$[-\epsilon,\epsilon]$,
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and let $J_\delta$ be a smooth function of
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$x$ and $t$ with integral $1$ and support in
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$[-\delta,\delta]\times[-\delta,\delta]$; $\delta$ and $\epsilon$ are
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positive numbers to be specified later.
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We choose $z=z^{\epsilon\delta}$ to satisfy
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&z_t+(\delta+J_\delta*\phi[u,u^h])z_{xx}=0,\qquad x\in\Bbb R,\;0
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&z(x,T)=j_\epsilon(x-x_0).
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The conclusion of the theorem now follows from (2.1) and the fact that
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|j_\epsilon*\Delta u(x_0,t)-\Delta u(x_0,t)|\leq C\epsilon^\alpha,
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which follows from Assumption 2.
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\example{Example\/ {\rm 1}} This is an example of an example.
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\remark{Remark\/ {\rm 1}} Examples are set the same as definitions in
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and the same as proofs in others. What convention does this style follow?
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Sometimes you want to include a figure, as in Fig.~1.
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\def\Bif{{\bf if\/ }}\def\Bwhile{{\bf while\/ }}\def\Belse{{\bf else\/ }}
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\settabs\+\qquad&\qquad&\qquad&\qquad&\cr
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\+\smc Tree Partition Algorithm \{\cr
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\+&Let stack size denote the number of nodes in the\cr
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\+&&subtrees stored temporarily on the local stack\cr
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\+&pop I from global stack\cr
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\+&set stack size := 0\cr
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\+&\Bwhile (stack size $\leq$ max size and stack size +
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I$\rightarrow$tree size $>$ 3 (max size)) \{\cr
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\+&&process I as an interior node\cr
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\+&&let min tree be the smaller of the subtrees of the two children of I\cr
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\+&&let max tree be the larger of the subtrees of the two children of I\cr
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\+&&\Bif (min tree$\rightarrow$tree size + stack size $>$ 3 (max size)) \{\cr
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\+&&&push min tree onto the global stack\cr
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\+&&&push min tree onto the local stack\cr
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\+&&&set stack size := stack size + min tree$\rightarrow$tree size\cr
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\+&&set I := max tree\cr
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\+&\Bif (I$\rightarrow$tree size + stack size $>$ 3 (max size)) \{\cr
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\+&&push I onto the global stack\cr
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\+&&push I onto the local stack\cr
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\+&Process all subtrees on the local stack\cr
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\botcaption{Fig.~1} Tree partition algorithm Tree partition algorithm
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Tree partition algorithm Tree partition algorithm Tree partition algorithm
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Tree partition algorithm Tree partition algorithm.\endcaption
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We finish with a table of all SIAM journals.
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\topcaption{Table 1}{SIAM journal acronyms and titles}\endcaption
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\settabs\+\indent&Acronym\indent&Title&\cr
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\hbox to \hsize{\hrulefill}
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\hbox to \hsize{\hrulefill}
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\+&SINUM&SIAM Journal on Numerical Analysis&\cr
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\+&SIREV&SIAM Review&\cr
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\+&SIMA&SIAM Journal on Mathematical Analysis&\cr
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\+&SIMAX&SIAM Journal on Matrix Analysis and Applications&\cr
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\+&SICOMP&SIAM Journal on Computing&\cr
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\+&SISC&SIAM Journal on Scientific Computing&\cr
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\+&SIOPT&SIAM Journal on Optimization&\cr
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\+&SIAP&SIAM Journal on Applied Mathematics&\cr
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\+&SICON&SIAM Journal on Control and Optimization&\cr
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\+&SIDMA&SIAM Journal on Discrete Mathematics&\cr
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\+&TVP&Theory of Probability and Its Applications&\cr
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\hbox to \hsize{\hrulefill}
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\by L. A. Caffarelli and A. Friedman
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\paper Regularity of the free boundary of a gas flow in an
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$n$-dimensional porous medium
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\jour Indiana Math. J.
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\by R. DeVore and B. Lucier
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\paper High order regularity for solutions of the inviscid Burgers equation
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\inbook Nonlinear Hyperbolic Problems
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\procinfo Proceedings of an Advanced Research Workshop, Bordeaux,
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\bookinfo Lecture Notes in Mathematics
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\eds C. Carasso, P. Charrier, B. Hanouzet, and J.-L. Joly
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\publ Springer-Verlag
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\publ Cambridge University Press
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\by R. A. DeVore and V. A. Popov
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\paper Interpolation spaces and non-linear approximation
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\inbook Function Spaces and Applications
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\bookinfo Lecture Notes in Mathematics
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\procinfo Proceedings of the US--Swedish Seminar held in Lund,
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Sweden, June 15--21, 1986
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\eds M. Cwikel, J. Peetre, Y. Sagher, and H. Wallin
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\publ Springer-Verlag
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\by R. A. DeVore and X. M. Yu
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\paper Nonlinear $n$-widths in Besov spaces
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\inbook Approximation Theory VI: Vol. 1
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\eds C. K. Chui, L. L. Schumaker, and J. D. Ward
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\by K. Hollig and M. Pilant
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\paper Regularity of the free boundary for the porous medium equation
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\paperinfo MRC Tech. Rep. 2742
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\book Approximation of Nonlinear Evolution Systems
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\manyby R. J. LeVeque
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\paper Convergence of a large time step generalization of Godunov's method
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for conservation laws
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\jour Comm. Pure Appl. Math.
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\by O. Rioul and M. Vetterli
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\paper Wavelets and signal processing
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\jour IEEE Signal Processing Magazine