LIMITATIONS

The current version of Istar has a number of limitations.  Some of them 
include:

#  Cannot import to KB from another KB.
#  The FIRSTOK inference method (Present Each To User) not yet
implemented.
#  Cannot use the Import-Text yet on items.
#  Cannot at present delete value names from an attribute type; can only 
add them.
#  Certain obscure conversions between value types do not work fully; best 
to try them out before you use them.  e.g. Float to Odds.
#  The new text/document facility is at present very limited.


BUGS

This is a list of some bugs you should be aware of.

#  (Can be misleading to user)  The explanation of a relationship type is 
only accurate for simple types; the facility is yet to be finalized. 
Version 1.04 and earlier.

#  (Nuisance)  Recently I had things like DirOpus loaded, and went to load 
up three KBs with full size easels.  Then tried to 'rid' a KB and nothing 
happened.  Tried to quit and nothing happened.  Because I had run out of 
Chip memory and the small "Is it OK to rid the KB?" panel would not come 
up!  (Chip memory was down to 13k.)  But beware: there is no warning, and 
none can be given because the warning panel will not come up.

#  (Harmless limitation)  Various buttons are not operative yet:
      Clone item type
      Import text into item
      You might find others that either flash or do nowt

#  (Harmless limitation)  Conversion Float to Odds does not work.

#  (Could lead to unexpected results in your KB)  When a conversion does 
not work you do not get any warning of this fact.  What happens depends on 
the type of conversion, but often the result holds the bit pattern of the 
uncoverted value, which might of course seem like rubbish, or might hold 0. 
30 July 1996.

#  (Cosmetic, harmless; PARTLY FIXED)  Version 1.02:  A Form item does not 
space out the value gadgets properly always.  Some of them are too tall and 
overlap others.  2 August 1996.  This is being investigated.  It has been 
partly cured (still untidy) in Version 1.03.


CRASHES ENCOUNTERED

(Please: it you have it crash on you, send me details. 
Istar@basden.demon.co.uk).  The following crashes I have experienced and 
not yet found the cause of.

#  (1.04: Probably OK from 1.05. Can cause crash, but avoidable)  The 
resize KB facility can be a bit fragile and can cause a crash in version 
1.04.  This is because if the KB increases in size it moves in memory and 
therefore all the pointers into it must all be changed.  I *think* I have 
found all these, but I did once get a guru 81---5 (attempt to free memory 
already freed) when I quit the program.  I have a feeling it was something 
to do with resizing.  For this reason, before you attempt to resize you 
should close down all panels except that for the KB itself.



BUGS FIXED

BY VERSION 6 (Feb 1997)

#  (Nuisance to end user in versions 1.05 and earlier)  The Chooser 
inference method would only reset its attribute to unanswered every other 
time, not every time.  A bug in dealing with first (index) antecedent. 
Fixed after 1.05.

#  (Nuisance in version 1.04, corrected 1.041)  A bug entered V1.04 that I 
found two days after placing it on Aminet!  It would not allow you to 
change value types in the Attribute Details panel.  Immediately corrected 
it and placed new version 1.041 on Aminet.

#  Bug when adding new attribute to items with shown attributes.  The new 
one would be placed on top of old one.  Now it's OK; they are placed in a 
vertical column.


BY VERSION 1.05 (Jan 1997)

#  (A freeze if not a crash!)  There's an odd sort of bug when Istar runs 
up on some machines.  It's perfectly OK on the three 1200s that I have 
tried it on (020 and 030).  But when I run it up on my 4000 it comes up 
with the main easel and the SIT (Select Item Type) panel and all, but won't 
draw, and won't respond to clicks on the main control panel.  Until, that 
is, I click around on the SIT panel.  Sometimes dragging the listview 
scroll bar around helps, and then clicking to select an item type, 
sometimes clicking on the 'New' button.  Then there is a delay of a few 
seconds, and everything starts as normal.  Strange.  But, as I say, on my 
three 1200s it seems perfectly OK.  9.9.96: I have found a possible cause 
of this and corrected it, but have yet to try it out.  No, it does not work 
yet, Nov 1996.  I got an email to say that it froze their 3000 too.  While 
preparing 1.05 I found a slight error in the code, changed it, and then it 
seemed to work on my 4000 and 3000.  So hopefully it's now OK.


BUGS FIXED BY VERSION 1.04 (Nov 1996)

#  (Harmless Cosmetic)  When you change the name of an item, it doesn't 
redraw with the new name until F1 or next load.  Attribute names refresh 
OK.  Version 1.03 and before.

#  (Harmless Nuisance)  When trying to resize an item using right-shift, 
you have to place the mouse *exactly* on the edge of the box: hit-vicinity 
is zero.  Otherwise you will start to draw a link or move the box; if that 
happens then just hit escape.  Version 1.03 and before.  (Actually, it was 
not the need for exact positioning: it required a second attempt.  A bug in 
window switching.)

#  (Harmless cosmetic)  When you start drawing on the main easel and abort 
by hitting escape you get a beep-flash.  Don't worry: nothing is wrong. 
Version 1.03 and before.

#  (Harmless nuisance)  New facility in Version 1.03, Resizing of KBA, 
doesn't work; it leaves the KBA as it is.

#  (Harmless nuisance)  The Backup button on the KB Area panel (Version 
1.03) has no effect.

#  (Harmless cosmetic nuisance)  Renaming the KB Area sometimes leaves 
rubbish characters at the end.  Version 1.03.

#  (Harmless, cosmetic)  When you reset an attribute that is in the middle 
of a network it propagates the unanswered status OK, but does not show this 
change in status on the easel.  So if the Att is e.g. Bayesian and Shown it 
retains the solid black line.

#  (Frustrating but probably harmless)  Version 1.03:  When you have two 
KBs active, and go to the Item Type Panel, and hit the Left or Right 
RelTypes buttons nothing happens.  But when you get rid of all but one then 
the list of RelTypes appears OK.  5 August 1996.  This is being 
investigated.


BUGS FIXED BY VERSION 1.03 (Sep 1996)

#  FIXED.  Version 1.02:  Never press the three right hand gadgets of the 
name/meaning bar unless a knowledge base is present.  It will probably 
crash the machine or send it into an infinite loop since they assume one is 
present.  2 August 1996.  This has been corrected in version 1.03.

#  Version 1.02:  When redirecting a link the DAG cycle detection algorithm 
sometimes says there is a loop when there is not.  2 August 1996.  This is 
being investigated.  12 September 1996: I have found the bug: it 
occasionally searched from the wrong node.  Now it should be OK in Version 
1.03.

#  Version 1.02.  It occasionally crashed while linking two items.  I have 
found a bug that could do this, and corrected it.  Version 1.03 should be 
OK.


Copyright (c) Andrew Basden, 1996
