Dear GAP Forum,

This is to announce the release of GAP 4.7.7, which could be downloaded from

This release includes not only improvements and fixed bugs, but also two new 
GAP packages:

- json package by Christopher Jefferson, providing a mapping between the 
JSON markup language and GAP;

- SglPPow package by Bettina Eick and Michael Vaughan-Lee, providing the 
database of p-groups of order p^7 for p > 11, and of order 3^8.

Also, Windows users may now use the standard installer

which since GAP 4.7.6 became an official format for the GAP distribution 
for Windows. Alternative installers for Linux and OS X (BOB and GAP Rsync) 
will hopefully be updated later.

The overview of changes in GAP 4.7.7 versus GAP 4.7.6 is given below.

New features:

- Introduced some arithmetic operations for infinity and negative infinity.

- Introduced new property 'IsGeneratorsOfSemigroup' which reflects whether 
the list or collection generates a semigroup.

Fixed bugs which could lead to incorrect results:

- Fixed a bug in 'Union' (actually, in the internal library function 
'JoinRanges') caused by downward running ranges. [Reported by Matt Fayers]

- Fixed a bug where recursive records might be printed with the wrong 
component name, coming from component names being ordered differently 
in two different pieces of code. [Reported by Thomas Breuer]

- The usage of abs in src/gmpints.c was replaced by 'AbsInt'. The former 
is defined to operate on 32-bit integers even if GAP is compiled in 
64-bit mode. That lead to truncating GAP integers and caused a crash in 
'RemInt', reported by Willem De Graaf and Heiko Dietrich. Using 'AbsInt' 
fixes the crash, and ensures the correct behaviour on 32-bit and 64-bit 

Fixed bugs that could lead to break loops:

- A problem with 'ProbabilityShapes' not setting frequencies list for 
small degrees. [Reported by Daniel Błażewicz and independently by Mathieu 

- An error when generating a free monoid of rank infinity. [Reported by 
Nick Loughlin]

- Several bugs with the code for Rees matrix semigroups not handling 
trivial cases properly.

- A bug in 'IsomorphismTypeInfoFiniteSimpleGroup' affecting one particular 
group due to a misformatting in a routine that translates between the 
Chevalley type and the name used in the table (in this case, "T" was 
used instead of ["T"]). [Reported by Petr Savicky]

Other fixed bugs:

- The 'Basis' method for full homomorphism spaces of linear mappings did 
not set basis vectors which could be obtained by 'GeneratorsOfLeftModule'.

- A problem with 'GaloisType' entering an infinite loop in the routine for 
approximating a root. [Reported by Daniel Błażewicz]

- Fixed the crash when GAP is called when the environment variables HOME 
or PATH are unset. [Reported by Bill Allombert]

In addition to the two new packages mentioned above, GAP 4.7.7 distribution 
includes updates of 17 other GAP packages:

Package name          | Version     | Date
Circle                | 1.5.3       | 13/02/2015 
CoReLG                | 1.20        | 02/12/2014  
gpd                   | 1.31        | 17/12/2014  
GradedModules         | 2015.01.30  | 30/01/2015  
HomalgToCAS           | 2015.02.03  | 03/02/2015 
idrel                 | 2.21        | 10/12/2014 
json                  | 0.8.2       | 08/02/2015 
kan                   | 1.11        | 10/12/2014 
LiePRing              | 1.8         | 08/11/2013   
LocalizeRingForHomalg | 2014.11.20  | 20/11/2014 
MatricesForHomalg     | 2015.02.03  | 03/02/2015 
Modules               | 2015.02.10  | 10/02/2015 
RingsForHomalg        | 2015.02.10  | 10/02/2015 
Semigroups            | 2.2         | 20/01/2015 
SglPPow               | 0.9         | 21/11/2014  
TomLib                | 1.2.5       | 21/11/2014  
ToolsForHomalg        | 2014.12.08  | 08/12/2014  
Wedderga              | 4.7.2       | 24/11/2014   
XMod                  | 2.31        | 17/12/2014  

We encourage all users to upgrade to GAP 4.7.7. If you need any 
help or would like to report any problems, please do not hesitate 
to contact us at

Wishing you fun and success using GAP,

The GAP Group

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