- Timestamp:
- Dec 31, 2007, 2:47:22 AM (18 years ago)
- Author:
- neil.c.c.brown
- Message:
-
Tidied up the slides about the dark shadow -- should be much more readable now
- File:
-
- 1 edited
- docs/trunk/omega-test-slides/omega-test.tex (modified) (2 diffs)
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docs/trunk/omega-test-slides/omega-test.tex
r141 r142 489 489 \begin{frame}[fragile] 490 490 \frametitle{Integers} 491 \includegraphics[width=100mm]{Omega-Test-Number-Line.png} 492 493 $\neg \exists x: a\beta \leq abx \leq b\alpha \implies b\alpha - a\beta \leq ab - a - b$ 494 495 Using $A \implies B = \lnot B \implies \lnot A$: 496 491 \only<1>{ \begin{center} \includegraphics[width=100mm]{Omega-Test-Number-Line.png} \end{center} } 492 \only<1-2>{ \begin{align*} 493 % I can explain it without this equation, and I think it's easier that way: 494 %\only<1>{\neg \exists x: a\beta \leq abx \leq b\alpha &\implies b\alpha - a\beta \leq ab - a - b \\ } 495 \only<1-2>{ b\alpha - a\beta > ab - a - b &\implies \exists x: a\beta \leq abx \leq b\alpha \\ } 496 \only<2>{ b\alpha - a\beta \geq ab - a - b + 1 &\implies \ldots \\ 497 b\alpha - a\beta \geq (a - 1)(b - 1) &\implies \ldots } 498 \end{align*} } 497 499 \note{$A \implies B$ 498 500 … … 503 505 $\lnot B \implies \lnot A$ (by definition) 504 506 } 505 506 $b\alpha - a\beta > ab - a - b \implies \exists x: a\beta \leq abx \leq b\alpha$ 507 508 $b\alpha - a\beta \geq ab - a - b + 1 \implies \ldots$ 509 510 $b\alpha - a\beta \geq (a - 1)(b - 1) \implies \ldots$ 511 512 Term this constraint $C_D$. $\operatorname{hasIntSol}(C_D) \implies \exists x: a\beta \leq abx \leq b\alpha$. 513 Therefore $\operatorname{hasIntSol}(C_R) \land \operatorname{hasIntSol}(C_D) \implies \operatorname{hasIntSol}(C)$ 514 515 N.B. $a = 1 \vee b = 1 \implies b\alpha - a\beta \geq 0 \implies b\alpha \geq a\beta$ 516 507 \only<2> 508 { 509 \begin{itemize} 510 \item Term this constraint $C_D$ (the dark shadow). $C_D$ has an integer solution $\implies \exists x: a\beta \leq abx \leq b\alpha$ 511 \item If both $C_R$ and $C_D$ have an integer solution, so does $C$ 512 \item N.B. $a = 1 \vee b = 1 \implies b\alpha - a\beta \geq 0 \implies b\alpha \geq a\beta$ 513 \end{itemize} 514 } 517 515 518 516 \end{frame}
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