diff -r 7aec0986b229 -r 8f142ae324e2 Slides/Slides3.thy --- a/Slides/Slides3.thy Tue Jul 13 14:37:28 2010 +0100 +++ b/Slides/Slides3.thy Tue Jul 13 23:39:39 2010 +0100 @@ -131,7 +131,7 @@ \begin{frame}<1>[c] \frametitle{Higher-Order Unification} - State of the art: + State of the art at the time: \begin{itemize} \item Lambda Prolog with full Higher-Order Unification\\ @@ -961,13 +961,19 @@ \item The alternative rule - %\begin{center}\small - %\colorbox{cream}{ - %\smath{\{a.t \eqprob b.t'\}\cup P \redu{\id} \{\swap{a}{c}\act t \eqprob \swap{b}{c}\act t', a \freshprob t'\} \cup P}} - %\end{center} + \begin{center}\small + \colorbox{cream}{ + \begin{tabular}{@ {}l@ {}} + \smath{\{a.t \eqprob b.t'\}\cup P \redu{\id}}\\ + \mbox{}\hspace{2cm}\smath{\{\swap{a}{c}\act t \eqprob + \swap{b}{c}\act t', c \freshprob t, c \freshprob t'\} \cup P} + \end{tabular}} + \end{center} - - leads to a more complicated notion of mgu. + leads to a more complicated notion of mgu.\medskip\pause + + \footnotesize + \smath{\{a.X \eqprob b.Y\} \redu{} (\{a\fresh Y, c\fresh Y\}, [X:=\swap{a}{c}\swap{b}{c}\act Y])} \end{itemize} \end{frame}} @@ -1003,7 +1009,7 @@ \draw (0,0) node[inner sep=3mm,fill=cream, ultra thick, draw=red, rounded corners=2mm] {\color{darkgray} \begin{minipage}{9cm}\raggedright - {\bf Problem:} If we ask whether + {\bf One problem:} If we ask whether \begin{center} ?- type ([(x, T')], lam(x.Var(x)), T) @@ -1027,7 +1033,7 @@ \begin{frame}<1-> \frametitle{Equivariant Unification} - James Cheney + James Cheney proposed \begin{center} \colorbox{cream}{ @@ -1036,7 +1042,7 @@ \end{center}\bigskip\bigskip \pause - He also showed that this is undecidable in general. :( + But he also showed this problem is undecidable\\ in general. :( \end{frame}} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% @@ -1054,7 +1060,14 @@ Unfortunately this breaks the mgu-property: \begin{center} - + \smath{a.Z \eqprob X.Y.v(a)} + \end{center} + + can be solved by + + \begin{center} + \smath{[X:=a, Z:=Y.v(a)]} and + \smath{[Y:=a, Z:=Y.v(Y)]} \end{center} \end{frame}} @@ -1064,7 +1077,7 @@ text_raw {* %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \mode{ - \begin{frame}<1> + \begin{frame}<1>[c] \frametitle{HOPU vs. NOMU} \begin{itemize} @@ -1073,7 +1086,7 @@ \colorbox{cream}{\smath{HOPU \Rightarrow NOMU}} \end{center}\bigskip - \item Levi\bigskip + \item Jordi Levy and Mateu Villaret established\bigskip \begin{center} \colorbox{cream}{\smath{HOPU \Leftarrow NOMU}} \end{center}\bigskip @@ -1123,10 +1136,12 @@ \frametitle{Complexity} \begin{itemize} - \item Maribel Fernandez + \item Christiopher Calves and Maribel Fernandez showed first that + it is polynomial and then also quadratic - \item Levi - + \item Jordi Levy and Mateu Villaret showed that it is quadratic + by a translation into a subset of NOMU and using ideas from + Martelli/Montenari. \end{itemize} @@ -1143,14 +1158,18 @@ \begin{itemize} \item Nominal Unification is a completely first-order - language, but implements unification modulo $\alpha$.\medskip\pause + language, but implements unification modulo $\alpha$. + \textcolor{gray}{(verification\ldots Ramana Kumar and Michael Norrish)} + \medskip\pause \item NOMU has been applied in term-rewriting and - logic programming. I hope it will also be used in typing + logic programming. \textcolor{gray}{(Maribel Fernandez et + al has a KB-completion procedure.)} + I hope it will also be used in typing systems.\medskip\pause \item NOMU and HOPU are `equivalent' (it took a long time - and considerable time to find this out).\medskip\pause + and considerable research to find this out).\medskip\pause \item The question about complexity is still an ongoing story.\medskip @@ -1168,7 +1187,7 @@ \frametitle{ \begin{tabular}{c} \mbox{}\\[23mm] - \alert{\LARGE Thank you very much}\\ + \alert{\LARGE Thank you very much!}\\ \alert{\Large Questions?} \end{tabular}}