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#342 axiom from CVS not building on Fedora core 6 ←	↑	→ #344 Tube Plots

#343 Bug in FreeAbelianGroup

Edit detail for #343 Bug in FreeAbelianGroup revision 1 of 5

	1 2 3 4 5
Editor: Time: 2007/11/17 22:30:15 GMT-8
Note: Fixed in wh-sandbox Revision: 496

changed:
-
The order in 'FreeAbelianGroup' is broken and makes the domain unusable
(e.g., comparison of Set 'FreeAbelianGroup S' does not work properly)
For example here is a cycle::

  ----------------------------------------
  Z2:=FreeAbelianGroup Symbol         

  a:= a::FreeAbelianGroup Symbol         
  b:= b::FreeAbelianGroup Symbol
  z:= 0::FreeAbelianGroup Symbol

  a < -b 
  -b < z
  z < a
  ----------------------------------------

thus $a < -b < z < a$

\begin{axiom}
a:= a::FreeAbelianGroup Symbol         
b:= b::FreeAbelianGroup Symbol
z:= 0::FreeAbelianGroup Symbol

(a < -b)::Boolean 
(-b < z)::Boolean
(z < a)::Boolean
\end{axiom}

proposed patch in the last few lines of free.spad::

  545,546c545,546
  <         ta.gen < tb.gen => true
  <         ta.gen > tb.gen => false
  ---
  >         ta.gen < tb.gen => tb.exp > 0
  >         ta.gen > tb.gen => ta.exp < 0

apparently revlex order is intended but is not achieved in the current implementation,
as the sign of the trailing exponent is not taken into account.


From kratt6 Mon Apr 9 13:50:56 -0500 2007
From: kratt6
Date: Mon, 09 Apr 2007 13:50:56 -0500
Subject: Fixed in wh-sandbox Revision: 496
Message-ID: <20070409135056-0500@wiki.axiom-developer.org>

Status: open => fix proposed

The order in FreeAbelianGroup is broken and makes the domain unusable (e.g., comparison of Set FreeAbelianGroup S does not work properly) For example here is a cycle:

  ----------------------------------------
  Z2:=FreeAbelianGroup Symbol         

  a:= a::FreeAbelianGroup Symbol         
  b:= b::FreeAbelianGroup Symbol
  z:= 0::FreeAbelianGroup Symbol

  a < -b 
  -b < z
  z < a
  ----------------------------------------

thus

axiom
a:= a::FreeAbelianGroup Symbol

(1)

Type: FreeAbelianGroup? Symbol

axiom
b:= b::FreeAbelianGroup Symbol

(2)

Type: FreeAbelianGroup? Symbol

axiom
z:= 0::FreeAbelianGroup Symbol

(3)

Type: FreeAbelianGroup? Symbol

axiom
(a < -b)::Boolean

(4)

Type: Boolean

axiom
(-b < z)::Boolean

(5)

Type: Boolean

axiom
(z < a)::Boolean

(6)

Type: Boolean

proposed patch in the last few lines of free.spad:

  545,546c545,546
  <         ta.gen < tb.gen => true
  <         ta.gen > tb.gen => false
  ---
  >         ta.gen < tb.gen => tb.exp > 0
  >         ta.gen > tb.gen => ta.exp < 0

apparently revlex order is intended but is not achieved in the current implementation, as the sign of the trailing exponent is not taken into account.

Fixed in wh-sandbox Revision: 496 --kratt6, Mon, 09 Apr 2007 13:50:56 -0500 reply

Status: open => fix proposed