Index: doc/changes_in_singular4.texi
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+@comment this file contains the list of new features and difference between Singular 3.* and Singular 4.*
+
+The purpose of this section is to describe new features and changes
+between Singular 3-1-7 and Singular 4.* (formerly known as Spielwiese) both for developers 
+and Singular users. In what follows we will refer to the systems as Singular 3 and Singular 4.
+
+@menu
+* Notes for Singular users::
+* Notes for developers::
+* Building Singular::
+@end menu
+
+
+@c ---------------------------------------------------------------------------
+@node Notes for Singular users, Notes for developers, , Singular 3 and Singular 4 
+@subsection Notes for Singular users
+@cindex Notes for Singular users
+
+@subsubheading Coefficient rings
+@cindex Coefficient rings
+
+To allow for easy integration of new coefficient rings into Singular, the the way 
+coefficient rings are being handled has been redesigned.
+
+In general, the user syntax has not changed, however there are some changes in the behaviour of Singular:
+
+@c table @asis
+@itemize @bullet
+@item Minor changes in the output of coefficient ring description. Moreover the output of elements of certain rings has been improved (for example, reals).
+
+@item Algebraic and transcendental extensions of rationals and finite fields
+      have been reimplemented. In particular, the heuristics for clearing denominators and factoring out content
+      have been changed. In some cases this leads to a different, mathematically equivalent results of Groebner
+      bases and related computations. For example a Groebner basis element may differ by a unit.
+
+@item Most noteably, due to the redesign of the coefficient rings, if the user sets the minimal polynomial
+      all variables dependent on the current ring are deleted.
+
+@end itemize
+@c @end table
+
+@subsubheading Ring-dependent options
+@cindex Ring-dependent options
+
+Formally global Singular @ref{option} now belong to individual polynomial rings. This includes:
+
+@c table @asis
+@itemize @bullet
+@item @code{intStrategy}
+@item @code{degBound}
+@item @code{multBound}
+????
+@end itemize
+@c @end table
+
+Hence setting these options only affects the current ring. Be aware of this
+when switching between different rings, since the options affect the
+result of various computations (in particular Groebner bases).
+
+@subsubheading New libraries depending on Singular 4
+@cindex New libraries depending on Singular 4
+
+In Singular 4 there several new features are implemented within a
+dynamic module @code{syzextra.so}, not available in Singular 3. 
+It implements the low-level functions for Schreyer resolutions and many auxiliary functions.
+The following new libraries @ref{derham_lib}, @ref{schreyer_lib} depend on it:
+
+@c table @asis
+@itemize @bullet
+@item @ref{derham_lib} - computes de Rham cohomology
+@item @ref{schreyer_lib} - computes Schreyer resolution via several approaches. It also serves as a high-level wrapper to the dynamic module @code{syzextra.so}
+@end itemize
+@c @end table
+
+@subsubheading Path names
+@cindex Path names
+
+@c table @asis
+@itemize @bullet
+@item The tree structure of the binary Singular distribution has been changed. The typical tree now looks as follows:
+      *** add tree ***
+
+@item Accordingly Singular search paths (where Singular searches for libraries, dynamic modules, etc.) have been changed. You can display them by calling Singular by @code{Singular -v}.
+
+@end itemize
+@c @end table
+
+@subsubheading Library versioning
+@cindex Library versioning
+
+Due to switching from Subversion to GIT revision control system for the Singular source code, 
+library version variables (displayed when loading a library) have changed (to include the GIT commit IDs).
+
+
+@subsubheading New orderings for modules
+@cindex New orderings for modules
+
+The now can assign weights to module components, when defining a monomial ordering. For example
+
+@code{> ring R = 0, (x,y,z), (am(1,2,3,   10,20,30,40), dp, C);}
+@code{> deg(x*gen(1));}
+@code{11}
+
+will assign weights 1,2,3 to x,y,z respectively, and weights 10,20,30,40,0,0,... to 
+components of any free module defined over R. This ordering will first sort
+by this weighted degree, then by dp on the ring monomials and then will give priority 
+to the large component index.
+
+@subsubheading Future benefits of Singular 4
+@cindex Future benefits of Singular 4
+
+The redesign of Singular will allow us to provide new features in the future, for example:
+
+@c table @asis
+@itemize @bullet
+@item Interpreter type for coefficient rings.
+@item User defined coefficient rings.
+@item Improved syntax for defining polynomial rings.
+@end itemize
+@c @end table
+
+
+
+
+@c ---------------------------------------------------------------------------
+@node Notes for developers, Building Singular, Notes for Singular users, Singular 3 and Singular 4
+@subsection Notes for developers
+@cindex Notes for developers
+
+There has been an entensive process of refactoring, redesign and modularization
+of Singular to facilitate easier maintenance and future development:
+
+@c table @asis
+@itemize @bullet
+@item Build System : automake, libfac has been integrated into Factory
+@item Removed MP (Multi protocol) in favor of SSI links.
+@item Separation/modularization into libraries and packages 
+@c add diagram as an image?
+@item For easy integration of new coeffcient rings,
+we defined a generic interface for coefficient 
+rings and a supporting framework for making them
+accessible to the user.
+
+In particular we have separated everything related to coeffcient rings into a separate library @code{libcoeffs}.
+
+@end itemize
+@c @end table
+
+
+
+@subsubheading Changes to build system
+@cindex Changes to build system
+
+@c ---------------------------------------------------------------------------
+@node Building Singular, , Notes for developers, Singular 3 and Singular 4
+@subsection Building Singular
+@cindex Building Singular
+
+The user can build and install Singular with the following standard UNIX-like procedure:
+
+@c table @asis
+@itemize @bullet
+@item Download and extract the latest official source package (.tar.gz).
+@item Run the configure script, for instance, @code{./configure}.
+@item Build Singular by running @code{make}.
+@item Install Singular by running @code{make install}.
+@end itemize
+@c @end table
+
+In contrast to Singular 3, there are now many more configuration options.
+
+All possible options for configure can be seen by running the configure script with
+option @code{--help}. On a multicore compute consider running make with the 
+option @code{-f [cores]}.
+
+@c ---------------------------------------------------------------------------
