<div dir="ltr"><p dir="auto" style="box-sizing:border-box;margin-bottom:16px;color:rgb(31,35,40);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","Noto Sans",Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji";font-size:14px;margin-top:0px">Dear support team,</p><p dir="auto" style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(31,35,40);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","Noto Sans",Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji";font-size:14px">First of all, thank you so much for your interesting work to develop PyGCGOpt. I am working on a variant of the parallel machine scheduling problem with the Pyomo package on Google-Colab. By default, everything works well, but when I want to run some moderate problems its default solver, "CBC", cannot execute well. Since I have tried to install SCIP by Pyscipopt package and use the following method to call that.</p><blockquote style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex" class="gmail_quote">!conda install --channel conda-forge pyscipopt<br>...<br>SolverFactory('scip').solve(m, tee= True).write()</blockquote><p dir="auto" style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(31,35,40);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","Noto Sans",Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji";font-size:14px"><br></p><p dir="auto" style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(31,35,40);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","Noto Sans",Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji";font-size:14px">It takes around 4 (mins) to solve the problem optimality. As I have worked with Pygcgopt on Colab, I tried to solve the problem within a separate notebook by calling:<br></p><blockquote style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex" class="gmail_quote">m = Model("PMSPPC")<br>m.readProblem("PMSPPC.lp")<br>m.printVersion()<br>m.redirectOutput()<br>m.setMinimize()<br>m.optimize()</blockquote><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(31,35,40);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","Noto Sans",Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji";font-size:14px"><br></p><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(31,35,40);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","Noto Sans",Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji";font-size:14px">The problem was solved in seconds!!! (say less than 20 secs and I think in the default mode). Now, I am willing to call GCG from the Pyomo package. To do this I called that by <code class="gmail-notranslate" style="box-sizing:border-box;font-family:ui-monospace,SFMono-Regular,"SF Mono",Menlo,Consolas,"Liberation Mono",monospace;font-size:11.9px;padding:0.2em 0.4em;margin:0px;white-space:break-spaces;border-radius:6px">!conda install --channel conda-forge pygcgopttried</code> and the methods like:<br></p><blockquote style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex" class="gmail_quote">1) SolverFactory('scipgcg').solve(m, tee= True).write()<br> 4) SolverFactory('scip-gcg').solve(m, tee= True).write()<br>2) SolverFactory('gcg').solve(m, tee= True).write()<br>3) SolverFactory('Pygcgopt ').solve(m, tee= True).write() </blockquote><p style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(31,35,40);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","Noto Sans",Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji";font-size:14px"><br></p><p dir="auto" style="box-sizing:border-box;margin-top:0px;margin-bottom:16px;color:rgb(31,35,40);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","Noto Sans",Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji";font-size:14px">But, neither of them can be calling the solver and already throw some errors like:</p><blockquote style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex" class="gmail_quote">RuntimeError: Attempting to use an unavailable solver.<br>The SolverFactory was unable to create the solver "scipgcg"<br>and returned an UnknownSolver object.  This error is raised at the point<br>where the UnknownSolver object was used as if it were valid (by calling<br>method "solve").<br>The original solver was created with the following parameters:<br>        executable: scipgcg<br>   type: scipgcg<br> _args: ()<br>     options: {}</blockquote><div class="gmail-snippet-clipboard-content gmail-notranslate gmail-position-relative gmail-overflow-auto" style="box-sizing:border-box;color:rgb(31,35,40);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","Noto Sans",Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji";font-size:14px;overflow:auto"><br></div><div class="gmail-snippet-clipboard-content gmail-notranslate gmail-position-relative gmail-overflow-auto" style="box-sizing:border-box;color:rgb(31,35,40);font-family:-apple-system,BlinkMacSystemFont,"Segoe UI","Noto Sans",Helvetica,Arial,sans-serif,"Apple Color Emoji","Segoe UI Emoji";font-size:14px;overflow:auto"><p dir="auto" style="box-sizing:border-box;margin-top:0px;margin-bottom:16px">I was wondering if, how can I call the GCG within Pyomo?</p><p dir="auto" style="box-sizing:border-box;margin-top:0px;margin-bottom:0px">Best regards<br style="box-sizing:border-box">Abbas</p></div></div>