get_alg,interface.html

The get_alg - graphical interface

Getting started

A function call get_alg(a) passes the algebra a to an external program, which then displays this algebra in a separate window. If no argument is given no algebra will be shown.
You then can edit, respectively input a quiver Q, i.e. vertices, arrows and relations, corresponding to the algebra.
An algebra here is given by the factor kQ/I, where k is a field, Q is a quiver and I is an ideal generated by the relations you set in the interface. The handling of the get_alg interface is as follows:

Main window

When you execute get_alg you get a window which is divided into five parts: the Taskbar, the Main input area, the Informationbar, the Scrollbars, and the Zoom button.

Taskbar The taskbar is the bar at the very top of the window. It is divided into three pulldown menus, a button to open a window to edit the relations, one select button and a Done button. There are also some short cuts defined. If you press the alternate key together with an underlined letter (FVERD) you get the same feature as if you click with the left mouse button on this letter.

The pulldown menus By a mouse click, it doesn't matter which button, the pulldown menus are opened. Here you can also navigate with the keyboard by using the cursor up and down keys and the Enter key.

File Here you can design your own algebra libraries. The format of the files the interface saves and loads can not be interpreted with CREP directly. Thus if you want to work in CREP with an algebra you have saved with the interface you first have to load it in the interface by calling get_alg and then press the done button (see also: Main window -> Taskbar -> The Done button).

With New you can delete the actual quiver and type in a new one.
With Load you open a FileSelector window (see also: File selector). Here you can load a quiver with relations you have previously saved.
With Save you open a FileSelector window (see also: File selector). You can store your quiver and your relations in a file with an arbitrary name but recommended is the extension .alg.
With Configuration you open the Configuration window of the interface. Here you can declare some variables of the interface, like the Maximum Vertex Count, the Maximum Arrow Count, the Double Click Time, the Matrix Size Warning Limit (this is not needed up to now) and the Load Buffer.
If you run into memory problems increase or decrease this values.
With About you get the authors, the version, and some other information.
With Exit you leave the interface. If you haven't exported your quiver before, nothing is send back to crep (see also: Main window -> Taskbar -> Export).

View Here you can determine how the quiver looks like.

With Fit to Screen the quiver is zoomed in such a way that it fits nicely in the Main input area.
With Zoom you can zoom in the quiver.
With Zoom Out you can zoom out of the quiver
With Redraw the quiver is redrawn. This is only needed if you think something looks strange.
With the toggle Show Vertex Numbers you can decide whether or not the vertex numbers should be displayed.
With the toggle Show Arrow Numbers you can decide whether or not the arrow numbers should be displayed.
With the toggle Draw Arrows as Arcs you can decide in what your arrows should look like. They are defined by the start and end point and a third point. The toggle defines whether the interface should draw an arc through these points or connect them with lines.
With the toggle Move Arrows with Vertices you can decide whether the third defining point of an arrow is also moved or not if the arrow is moved.

Export Here you can export your quiver in the internal format used by the function get_alg for communication with its interface. Afterwards you can leave the get_alg interface with Exit in the File menu (see also: Main window -> Taskbar -> The pulldown menus -> File).
A shortcut for this procedure is provided by the Done button

Relations This button opens and closes the relations window (see: Relations window).

The select button With a right or middle mouse click the possible modes are cyclically selected. By a left mouse click you get a menu where you can specify the mode you would like to have. For a description of the modes see also: Main window -> Main input area. The possible modes are Move Mode, Delete Mode and, if the relations window is open, Select Mode.

The Done button By a left mouse click on the Done button you leave the get_alg interface. Now you can go on with your work in CREP. This is the best way to leave the interface.

Main input area

In this area your quiver is displayed. The behaviour of your mouse depends on the setting of the select button in the Taskbar (see also: Main window -> Taskbar -> The select button).

Move Mode In this mode the left mouse button adds a vertex to your quiver in the main input area by two mouse clicks.
With the first left mouse click you select the start point of the arrow and with a second left mouse click you specify the end point of the arrow (see also: Main window -> Informationbar).
With a middle mouse click you add a vertex to the quiver in the main input area.
With a right mouse click you can move arrows and vertices in the following way. If you press the right mouse button near to a vertex and hold the button, you get the vertex and by depressing the button you set the vertex to the new position. The motion of the arrows is defined by the menu point Move Arrows with Vertices but they will never lose their start and end points (see also: Main window -> Taskbar -> The pulldown menus -> View).
If you press the right mouse button near to an arrow you can define a third point of this arrow where it should go through. if the arrows are drawn as arcs, the arc is defined by the start, the end and this third point. If the arrows are drawn as lines this third point defines an edge of the arrow. This is only needed for a nice look of the quiver.
Both, arrows and vertices, are labeled with increasing numbers. The label of an arrow is set near the third point the arrow passes through.

Delete Mode The only difference to the Move Mode is the behaviour of the right mouse button. With a double click on an arrow or vertex you can delete the arrow or vertex, resp. But a vertex can only be deleted if it is not the start or end point of an arrow and an arrow can only be deleted if it is not part of a relation (see also: Relations window).

Select Mode This mode is only available if the relations window is open (see also: Relations window).
In this mode you can select a path in the quiver by specifying the arrows of the path with mouse clicks. The left mouse button appends an arrow to the path, the middle mouse button appends in the front of the path and the right mouse button deselects the last arrow or takes back the last action. In this way also arbitrary cycles can be selected. Normally the selected path is printed yellow, but this depends on your installation and computer system, e.g. you might have a monochrome screen...;-)

Informationbar The informationbar is the bar at the very bottom of the main window. Here is briefly printed how your mouse buttons are operating and on which vertex or arrow the operation would act.

Scrollbars If the quiver does not fit in the Main input area, you can focus on the area you want to edit with the scrollbars in the bottom and the right of the Main window.

Zoom At the bottom on the right there is a small button labeled Z. By pressing this button with the left mouse button you zoom in, with the right mouse button you zoom out of the quiver. By pressing the middle mouse button the quiver is zoomed in such a way that it fits on the screen (see also: Main window -> Taskbar -> View).

Relations window

In this window you can select the generating relations for the ideal I for your algebra. There are five areas which will be described now.
In the first area at the top on the left you can select the start vertex of your path. In the area to the right you can select the end vertex of the path.
At the bottom on the left the selected Path is shown in the Path Selection & Quiver Statistic area. First you see the number of the paths then the number of the start vertex, an arrow and the number of the end arrow. Then there is a colon and right beside this you can see the numbers of the arrows of the path. By the first two fields you can decide which paths you would like to see in this area. You can select a path with a left mouse click. The selected path is highlighted in yellow (the color depends on your installation and computer system). It is also drawn yellow in the Main input area (see also: Main window -> Taskbar -> The select button) and you can select your path also there.
In the next area at the top on the right there are several buttons.

With the Hide Button you hide the Relations window.
With the Refresh button the shown paths are newly calculated. This is necessary if you have made changes to the quiver while the Relations window is open.
With the Next Point Pair button you can go through all possible paths. First all paths with start vertex 1 and end vertex 1 are listed then all paths with start vertex 1 and end vertex 2 and so on.
With the Previous Point Pair button you cycle through all possible paths in the opposite direction.

Below these two buttons there is a select button, with which you can decide whether all paths, only circles or no circles should be shown. For the handling of a select button see Main window -> Taskbar -> The select button. But be warned that of course not all cycles can be shown because there all always infinitely many of them. That means if you want to select a cycle which is not shown, you have to use the Main input area (see also: Main window -> Main input area -> Select Mode).

The New Relation button adds the selected path to the Relations which are shown at the bottom on the right.
With the Add to Relation button you can build up the sum of two or more paths with the same start and end vertices. With a left mouse click you can select the relation to which you want to add another one.
With the Remove Relation button you can remove a selected relation.

In the fifth area at the bottom right, where the relations are shown, you can also change the coefficient of the relation, by typing them into the coefficient field and hitting the enter key.

Finally, with the Relation button, you can open a menu where you can delete all relations, add them by length, you can take such relations that your algebra gets pseudo Schurian and you can decide whether or not you want to list the empty paths and whether or not you would like to have scrollbars on the left side.

File selector

Here you can select the file you want to read or where you want to save your file. This window appears in some graphical user interfaces in CREP.
Description: At the top of the File Selector window the current Directory and a pattern is shown. In the area below this all directories and all files of the current directory which match the pattern are shown. If there are changes in the directory you can force an update of the view with the Rescan button.
You can either select a file by a left mouse click or directly type in the name of the file at the bottom of the window.
If you have selected a file to load or save press the enter key or the Ready button in the window.
Finally there is a Cancel button which closes the File Selector window with the arrow keys and the enter key of your board.

Known bugs

In the relations window the add paths by length feature doesn't work correctly.

BACK TO: start page of the crep online manual, get_alg