WHAT'S NEW (Version 4.1.1)

(i) clean-up all local variables that were not declared as such

(2) make linear solver silent by default

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WHAT'S NEW (Version 4.1)

(Only minor aesthetic changes that make the use
of "zb_prove" simpler and make Zeilberger do 
also what parGosper does).

(i) zb_prove produces proofs with more details by default

(ii) zb_prove also takes 3 arguments (it computes the fourth by itself)

(iii) Zeilberger also takes four arguments (in this case parGosper is invoked)


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WHAT'S NEW (Version 4.0)

(i) Bugs:
With this version I have removed an ugly bug
in the optimization related to constant factors 
(non-dependent on the summation variable).

(ii) Wrong input detection:
The package detects non-hypergeometric input
for "Gosper", "parGosper" and "Zeilberger".

(iii) New features:
This version adds some functions that produce 
human readable proofs of the results 
and some others that test the result produced by
"parGosper", "Gosper" and "Zeilberger":

(1) "gs_prove" proves the result of "Gosper" 
(2) "zb_prove" proves the result of "parGosper" and "Zeilberger"
(3) "zb_meaning" writes down the recurrence corresponding to
the output of "parGosper" and "Zeilberger"
(4) "zb_test" performs a test on a list of inputs for "parGosper".
REMARK: This is a sort of META-test because the test is checking its own result, in that it is computing a formal proof (certificate) of the result.

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WHAT'S NEW (Version 3.0)

The new version of the package adds the following features
to version 2.0:

(i) Gosper's algorithm for indefinite summation
available through the new commands: 
(1) "Gosper" (finds the rational certificate) 
(2) "AntiDifference" (finds the hypergeometric antidifference)
(3) "GosperSum" (sums over a given interval by invoking "AntiDifference")

Remark: Gosper's algorithm is now integrated in "Zeilberger" and it
is invoked by default as first attempt.

(ii) Warnings (about trivial solutions, terms not depending on the
recurrence variable, dimension of the solutions higher than one, etc...).

(iii) Numerical/Modular test for discarding zero-solution systems
in "parGosper" and "Zeilberger".

(iv) Lots of settings available (see "readme.txt" and "zeilberger_settings.mac").

(v)  Cleaner code.

(vi) More verbosity levels.

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WHAT'S NEW (Version 2.0)

(i) A few changes necessary to port the package from Macsyma to Maxima

(ii) Fewer bugs

(iii) Axel Riese's "filtering" optimization

