tl;dr: I would like to apply genetic algorithm to directed acyclic graphs that represents arithmetic operations. Thank you for hosts, speakers and all participants in ICFP2012. I had chance to make a lot of questions (c.f. [prize.jpg]) and receive lots of stimulating ideas. I have been working on automated parallel code generation and automated tuning for hydrodynamics http://iopscience.iop.org/1749-4699/5/1/015003 ; one of my next target is model acquisition in robotics: http://creativemachines.cornell.edu/sites/default/files/moriguchi11.pdf ; both deal with computations represented in forms of directed acyclic graphs c.f. [graph-1.png] [graph-2.png]. We would like to describe them easily in Haskell, but also to mutate (add random changes) and crossover (create a new graph by mixing other two graphs.) In my previous work, I used Monad to generate graphs and used the Functional Graph Library to explicitly modify the graphs. Now I have learned that there are more elegant methods to describe the computations with sharing. But are those method also enables easy editing of the graphs? That's my question. In [data-reify.hs] I tried Observed Sharing by Gill09. Apparently, sharing is lost once we try to modify the graph. $ runhaskell data-reify.hs let [(1,GraphMul 2 2),(2,GraphAdd 3 3),(3,GraphMul 4 5),(5,GraphVar "X"),(4,GraphVal 40)] in 1 let [(1,GraphMul 2 9),(9,GraphAdd 10 13),(13,GraphMul 14 15),(15,GraphVar "X"),...,(5,GraphVar "X"),(4,GraphVal 42)] in 1 In [GenericMain.hs] I tried PHOAS by Oliveria & Cook 2012. $ runhaskell GenericMain.hs Mu ( a => Fork "Add"(Fork "Sub"(b) (Empty)) (c) b => Fork "Mul"(c) (c) c => Fork "40"(Empty) (Empty) d => Fork "X"(Empty) (Empty) ) Mu ( a => Fork "Add"(Fork "Sub"(b) (Empty)) (c) b => Fork "Mul"(c) (c) c => Fork "42"(Empty) (Empty) d => Fork "X"(Empty) (Empty) ) This time, I can modify a node without loosing the sharing. How about edges? Can you write operations such as "Choose one of the edges that point to (c) and make it point to (d)" ? Is there any good methods to describe and modify structures that has sharing (if it helps, I don't need loops.)? Or, after all is the best way explicit manipulation of the graph structure? Both information are helpful to me. Thanks in advance, -- Takayuki MURANUSHI The Hakubi Center for Advanced Research, Kyoto University http://www.hakubi.kyoto-u.ac.jp/02_mem/h22/muranushi.html
