%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %% %W start.tex GAP documentation Joachim Neub"user %% %H $Id: start.tex,v 1.8 2003/06/11 16:41:06 gap Exp $ %% %Y Copyright (C) 1999, Lehrstuhl D fuer Mathematik, RWTH Aachen, Germany %% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \Chapter{How to Start?} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \Section{Starting XGAP} You begin an {\ITC} session by starting {\XGAP}. On most systems this is done by completing the provided line \begintt user@host:~> \endtt to \begintt user@host:~> xgap \endtt on the command line. Ask your system administrator if this does not work. This command will create a new window, the so called {\GAP} Window, in which {\GAP} is awaiting your input. During a typical {\ITC} session various windows will be opened to display the involved tables and further information. The size of the characters displayed in these windows and hence the sizes of the windows themselves are determined by the so-called *fonts* used. The {\XGAP} package knows five different fonts, `tiny', `small', `normal', `large', and `huge' (see the {\XGAP} manual for details), but the {\ITC} routines use only two of them, namely `small' and `normal'. So, if the default {\ITC} window sizes are inconvenient for you, you need only to change the values of these two fonts. You may do this by starting {\XGAP} with one or two additional arguments of the form \"`-small <font>'\" or \"`-normal <font>'\" where <font> has to be a font which is known to your system. You can get a list of all available fonts via the command \begintt user@host:~> xlsfonts \endtt Example: \begintt user@host:~> xgap -small 6x12 -normal 8x13 \endtt In particular, you should use this option to change the fonts if the default fonts of {\XGAP} do not work properly in your local installation (this may happen in some rare cases where there are too few or too many fonts). %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \Section{Starting ITC} At the top of the {\GAP} Window opened by {\XGAP} you will see a ``title bar'' with three buttons: `GAP', `Run', and `Help'. Clicking either of these will pop up a menu, in which you may choose between several options. You can always interrupt a computation by making the {\GAP} Window active and pressing <CTRL-C>. You will get the same effect selecting `Interrupt' in the `Run' menu. In the {\GAP} Window, as usual, the {\GAP} prompt \begintt gap> \endtt will indicate that {\GAP} is awaiting your input. If it is not loaded automatically, first load the {\ITC} package by \begintt gap> RequirePackage( "itc" ); \endtt See~"ref:RequirePackage" in the {\GAP} Reference Manual. Then you may input a finitely presented group, say <g>, and a subgroup, say <h>, of it, the cosets of which you want to enumerate using {\ITC}. The format of this input is the same as usual in {\GAP}, see Chapter "ref:Finitely Presented Groups" of the {\GAP} reference manual for the details. {\ITC} will in several of its windows have to display generators of the free group which is used to describe the presentation. Note that {\ITC} will use the *names* of the generators of this free group, if these names consist of at most three symbols. Otherwise {\ITC} will use names of the form $g1$, $g2$, ... up to at most $g99$ for the generators of the free group (if the group has more than 99 generators, an error message will be given). A choice of short and easily distinguishable names for the generators of the free group is hence advisable. Now you are ready to start the {\ITC} using the command `InteractiveTC'. \>InteractiveTC( <g>, <h> ) F Called with a group <g> and a subgroup <h>, this will open the ``Coset Table Window'', which really serves a multiple purpose: \beginlist \item{--} It shows the Coset Table and allows certain operations by mouse click in this Coset Table. We will describe the details in Section "The Coset Table" of Chapter "The Tables". In this chapter also a description of all other tables is given that can be shown on the screen by {\ITC}. \item{--} Directly below the Coset Table space is left for one row of text in which some warnings will be given (in red) by {\ITC} if the user tries to invoke actions that in the present state are not possible, e.~g. if the user tries to call the short-cut function while the tables have not yet closed (see Section~"Warnings"). \item{--} It provides up to date information on the state that an interactive coset enumeration has reached in the ``Information Line'' (see~"The Information Line"). \item{--} It also provides a number of buttons which can be used in the interactive handling of a coset enumeration by {\ITC}. We will describe this aspect in a separate chapter ``Buttons and Menus'' (Chapter~"Buttons and Menus"). \endlist The initial table size for the {\ITC} Coset Table is set by default to 1000. You can change this default table size using the menu entry `change default table size' in the menu of the top button `Settings', (see~"change default table size"). If during a run of a CE the table size does not suffice, you can extend it using the menu entry `extend table size' (see~"extend table size") in the same menu. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %% %E