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- DRIVING ISTAR
-
- WHAT DO I NEED TO START IT?
-
- Normally you don't need to bother about this lot as they are set up during
- installation and Amiga startup. But if something goes wrong then this list
- might help.
-
- # assign KBTools: to some directory for best effect
- # iff.library
- # asl.library is needed for saving etc. (supplied with Amiga 1200)
- # CGTimes Font
- # Topaz 11 Font
- # Topaz 8 Font (supplied with any Amiga)
-
-
- HOW DO I START IT?
-
- This describes the normal start of Istar, from WorkBench.
-
- (If you are operating with low memory, such as a base A1200, then refer to
- the section below on 'Starting with Low Memory'. If you start from CLI, a
- few options are available in Version 1.04 onwards; see later.)
-
- 1. Double click on the Istar icon.
-
- 2. You will be presented with a grey Control Screen part way up the view.
- Initially this has 'Istar' on its title bar but that is soon obscured by a
- horizontal strip and, at the left, the Initial Control Panel.
-
- 3. Click the 'New' button, and two things will happen. First another
- screen, a large blank white one appears. This is the Easel on which you
- draw your KB (knowledge base). And, on the Control Screen, another panel
- appears with columns of buttons and two list gadgets. (If you are
- operating with limited memory, the standard Easel size (30 by 24 inches)
- might be too large, and you will have to alter the Prefs before clicking
- the New button.)
-
- Here are a few instructions to get you started ...
-
- 4. Draw a box by pressing Left Mouse Button (LMB) over Easel, a box
- appears, move mouse around to place it, then release LMB. (Do not click
- it; clicking does something else.)
-
- 5. Draw another box, to the right of first one.
-
- 6. Press LMB over the right hand edge of the left-hand box, and you will
- see a short line appear from your mouse pointer to a point one quarter the
- way into the box. This line follows the mouse as you move it. Move until
- line is over the right-hand box and release. If you want to insert a bend
- in your line, hit Space bar when end of line is where you want the bend.
- The left-hand box is called the antecedent of the right, and the right is
- the consequent of the left.
-
- 7. (To escape from any operation you have started but don't want, hit the
- Escape key. Then release the mouse button.)
-
- That's the basic mechanism, and the whole knowledge base can be drawn like
- that. Not too bad, is it?
-
-
- GOING FURTHER
-
- 8. Various modifications of the diagram are possible:
-
- a) Move a box by pressing LMB over the centre of the box. Dotted
- skeleton of the box and all its connecting links appears. Move mouse
- and this lot follows. Release in new position. (Note that boxes can
- overlap, though it is usually not wise to do so; overlapping is
- usually reserved to collections of boxes that are closely related
- semantically.)
-
- b) Bend a drawn link by pressing LMB over a link. Dotted bent line
- follows mouse to new position; release. Pressing LMB over existing
- bend will just move the bend to new position.
-
- c) To redirect a link to another box, delete a box, delete a link,
- delete a bend from a link: see below.
-
- 9. Entering detail, e.g. Name and Meaning. Click the Right Mouse Button
- (RMB) over centre of box. (If you get a dotted box outline as in 7(a) then
- you haven't clicked fast enough; hit escape key, release MB and try again.
- You'll soon get the hang of it.) Up comes the Control Screen, showing an
- Attribute Detail panel with around fifty gadgets. Don't panic: you need
- only the top two: Label and Meaning; ignore the others for now. These are
- string gadgets which allow you to enter a name for the box and a longer
- meaning if you wish. For now, put something in both boxes - anything in
- that you like. Then click the OK button. The Control Screen returns and
- your box should display the new name.
-
- 10. Showing Meaning. Move the mouse over the box (do not press any mouse
- button). The Meaning text should appear in the horizontal window in the
- top of the Control Screen. Move mouse away, and it disappears. In this
- way, even when the box label text is too small to read you can easily see
- what a box means.
-
- 11. More antecedents. Draw another couple of boxes (see 3 above) near the
- left-hand box (above or below it) and link these to the right-hand box as
- in 5 above, so that it now has three or more antecedents. Best also to
- name them with different names as in 8 above.
-
- 12. Running the KB. Now click with the Left Mouse Button over the centre
- of the right-hand box. Up comes a small panel at the top of the Control
- Screen containing a few buttons, the Attribute Action panel. The two
- buttons on the left are: Reset and Infer, which allow you to run the KB.
- Hit Reset, then hit Infer. Up comes a User Question panel, with text at
- the top ("No text for xxxx"; we can change that, below), a large central
- Value gadget and an large OK gadget to right, with a few others. Enter a
- Value and press OK. Then a similar panel should appear for the next
- attribute. And the next. If you have three left-hand boxes feeding into
- the right-hand one you should get three such User Question panels.
-
- 13. Seeing the result. When the question sequence has finished, the
- Attribute Action panel is still there. Hit the Data button, and you are
- taken to the Attribute Details panel. The result should be shown on the
- second row in the middle - and it should be the sum of all the values you
- entered during the question sequence.
-
- 14. Selecting the inference method. The inference method is the way the
- values found in the antecedent are combined to give a value to the
- consequent. The default for an integer consequent is addition. But this
- can be changed. On the Attribute Details panel there are three radio
- buttons on the left hand side, with the middle selected: 'Inference'. To
- its right is a small button with the name of the inference method, 'X = A +
- B + C ..", indicating addition. Hit the button and a list of different
- inference methods is presented. Choose one - say multiplication - and hit
- its OK button.
-
- 15. Now hit the OK-Act button; this is similar to OK, but takes you to the
- Attribute Action panel directly, having stored the new inference method in
- the attribute. As in 10, hit Reset then Infer to get the sequence of
- questions. Their values remain, so you need only hit OK for each. Hit
- 'Data..' to see the new value, which should be the product of your values.
-
- 16. Suppressing irrelevant information. Note that Istar only asks
- questions that it needs to, and thus avoids asking irrelevant ones. With
- multiplication this happens if one of the antecedents is zero - we then
- know the consequent will be zero, whatever values the remaining antecedents
- take, so there is no point asking them. Try it. (If you forget how, go to
- the Attribute Action panel of the consequent, hit Reset and Infer. Then
- put the second User Question value to 0 and hit OK. The third should not
- be asked.)
-
- 17. Control Screen. Whenever you want to access the Control Screen, click
- the Gadget showing two arrows at top left of the Control Screen. Up it
- comes. Click it again, and it parks back down the bottom. Alternatively,
- you can drag the Control Screen up and down manually using the two-pixel
- strip at the top of the Screen above the Meaning Strip. (Advanced use:
- You can change the parking position, e.g. to be lower and reveal more of
- the Easel. To do this, drag the Control Screen to where you want its
- parking position to be and then click the wee gadget immediately to the
- right of the up-and-down one. This records a new parking position.)
-
- 18. Different item types. Bring up the control screen. Top right window
- should show list of item types. Select Proportion, send Control Screen
- back down again, and draw box; should say 'Proportion'. Once you have
- several types of box in your Easel a quick way of changing type is to move
- mouse over a box of the type you want and hit 'T' key (for 'Type'). Try it
- over one of the original (Integer) boxes and note how the Item Type
- Selection changes to Integer. Draw, and you'll get an integer.
-
- 19. Automatic Type Conversion. Now link from right hand side of the
- Proportion box to one of the original (Integer) boxes. When the link is
- operative (see below) there will be an automatic conversion from Proportion
- to Integer (usually as a percentage 0 to 100).
-
-
- WHAT MORE IS THERE?
-
- 20. Lots more. That should more than get you started. But there's lots
- more:
-
- # Larger inference nets
- # Multi-step
- # Loop prevention
- # Scrolling
- # Zooming
- # Showing parts
- # Goal lists
- # Topics
- # Find
- # Forms
- # Creating new item types, multiple attributes
- # Creating new attribute types
- # Document creation
- # KB Dump, save, load.
-
-
- ** IF YOU WISH, YOU CAN NOW GO STRAIGHT TO <USING ISTAR>.
-
-
- STARTING FROM CLI
-
- To start Istar from CLI, simply type "Istar", maybe appending the version
- number if there is one. (I assume that you are familiar with paths etc. or
- how to activate a program in another directory.)
-
- Advanced use:
- From CLI you can start with various tracing on, by adding the
- parameters:
-
- "-tm" to trace some activity in the modules mechanism
- "-tu" to trace some UA module activity
- "-te" to trace some activity among easels
-
- so the command might be:
-
- Istar1.04 -tu -te
-
- This will usually only be of value when you suspect some bug and want to
- send me a trace of what happens.
-
-
- STARTING WITH LOW MEMORY
-
- The standard startup will just about start in a base 2 Mb A1200 as long as
- your Workbench screen is simple PAL 640 by 256 and only 4 colours. But in
- other situations, from Version 1.04 onwards, you can take action to reduce
- the amount of memory needed for your KB, before you create it. There are
- two ways of doing this.
-
- LOW MEMORY METHOD 1:
-
- This method involves starting up and immediately altering some of the
- preferences via the Prefs panel.
-
- # As soon as the Initial Control Panel comes up, click on the Prefs
- button to bring up the Preferences panel.
-
- # Alter the MinDSA figure (usually 50000 longwords) to e.g. 10000;
- this reduces the size of a new KB from around 20000 bytes to around
- 40000.
-
- # Alter the size of the Easel from 1920 by 768 to something smaller,
- such as 640 by 256. If its Depth is shown as 4 or higher reduce it
- to 3. Doing these reduces the amount of memory for the Easel of a
- new KB. The original size easel consumes around 200 kbytes for each
- bitplane, whereas 640 by 256 consumes only around 20 kbytes per
- bitplane.
-
- Note, though, that you should only do this if you can work with a small KB
- or easel. Also, doing this will not alter the sizes of KB or easel that
- are loaded from file.
-
- LOW MEMORY METHOD 2:
-
- Altering the preferences each time you load up can be tedious. So Istar
- can also load preferences from a file as it enters, which in version 1.04
- is the file IstarSys:IstarPrefs (that is, IstarPrefs in the drawer to which
- IstarSys: is assigned). So all you need to do is supply such a file,
- according to your needs.
-
- A file, IstarPrefs_LowMem is already supplied, so you need only enter
- the following command from a CLI:
-
- COPY IstarSys:IstarPrefs_LowMem IstarSys:IstarPrefs
-
- Bring up the Prefs panel to see the sizes it has given you. If you wish
- anything different then make up your own IstarPrefs file. There are many
- other Preferences that can be set via this file. See 'Preferences' section
- in the 'KBs' chapter for details.
-
-
- WHAT IS AN ITEM?
-
- An item in Istar is some focus of attention in the knowledge base. It is
- represented on the Easel by a box or group of boxes that move together. An
- item can have:
-
- # any number of attributes (so far they have had only 1)
- # relationships to other items
-
- On the Item Type list on the KB panel, select 'Contract Meaning'. This is
- an item expressed by two boxes, when you draw it on the Easel. The top one
- represents the item itself, the bottom one an attribute of the item.
-
- You can define your own item types. Let's try doing so. Hit the
- 'New' button below the Item Type list. A new panel, Create New Item Type
- (CNIT) comes up for an item type called 'Unnamed'. Change the name to
- 'Employee'.
-
- Now we will add attributes to the item type. To add each attribute
- to an item type we do three things:
-
- 1. Set the type
- 2. Set the name
- 3. Click the addition button just above the Type.
-
- So first, hit the Type wee button, and select String from the list that
- comes up; hit its OK button. Then in the Attribute name to the left of the
- Type, enter 'Name'. Now hit the button above Type. 'Name' will appear in
- the list in the middle of the panel. Now create an attribute called 'Age',
- of type Integer using the same steps. Now create an attribute called 'Day
- off' of Type 'Weekdays'. Lastly, create an attribute called 'Salary' of
- Type Integer.
-
- Then press OK (called Done in some versions) on the CNIT panel, and
- it disappears. Look at the SIT panel and you will see 'Employee' has been
- added at the bottom and should be selected (if not, select it).
-
- Now draw on the Easel and you should get a tall box group with five
- boxes: a smaller one at the top representing the employee itself, with four
- attribute boxes: Name, Age, Day off, Salary.
-
- Notice the similarity to databases: item = entity or record,
- attribute = attribute or field. Unlike many databases new item types can
- be created at any time. And (probably not this version) new attributes can
- be added to existing item types.
-
-
- WHAT IS AN ATTRIBUTE?
-
- An attribute is a holder of a value - such as Name, Age, etc. It can be of
- two types: in an item or a free attribute. Each attribute is expressed by
- a box. When you started above, you were drawing (creating) free
- attributes. When you drew the Employee box group you created an item with
- for attributes. Free attributes actually belong to a hidden item, for
- which there is no visible box.
-
- Attributes can be of a variety of types, which normally are defined
- in terms of value types (see below).
-
- It became clear during the INCA research project that the
- conventional picture, of items with several attributes, was not always
- appropriate. In an inference net a lot of items exist merely to support a
- single attribute, and so Istar developed the idea of 'free attributes', in
- which the item is still there for structural purposes but is de-emphasized
- and not shown on the easel. So in the Select Item Type panel the first set
- of items is normally a load of free attributes. They are represented by
- single boxes. Whether they are called attributes or items is immaterial.
-
-
- Copyright (c) Andrew Basden, 1996
-