AbstractToricVarieties, a package by Mike Stillman for linking abstract simplicial (normal) toric varieties to Schubert2, has been added.
AlgebraicSplines, a package by Gwyn Whieldon, Eliana Duarte, Daniel Irving Bernstein, and Daniel Irving Bernstein for splines on simplicial complexes, polytopal complexes, and graphs, has been added.
Chordal, a package by Diego Cifuentes and Pablo Parrilo for exploiting chordal structure, has been added.
CohomCalg, a package by Mike Stillman for providing an interface to CohomCalg software for computing cohomology of torus invariant divisors on a toric variety, has been added.
Complexes, a package by Gregory G. Smith and Mike Stillman for chain complexes, has been added.
GroebnerWalk, a package by Dylan Peifer for computing Gröbner bases via the Gröbner walk, has been added.
Matroids, a package by Justin Chen for computations with matroids, has been added.
NonminimalComplexes, a package by Frank Schreyer and Mike Stillman for obtaining the non-minimal strands of a non-minimal resolution of a homogeneous module, has been added.
NumericalImplicitization, a package by Justin Chen and Joe Kileel for computing invariants of images of polynomial maps, has been added.
PruneComplex, a package by Mahrud Sayrafi and Mike Stillman for pruning chain complexes over polynomial and local rings, has been added.
RandomMonomialIdeals, a package by Despina Stasi, Dane Wilburne, Tanner Zielinski, Daniel Kosmas, Parker Joncus, Richard Osborn, Monica Yun, and Genevieve Hummel for generating Erdos-Renyi-type random monomial ideals, has been added.
ReflexivePolytopesDB, a package by Mike Stillman for simple access to Kreuzer-Skarke database of reflexive polytopes of dimensions 3 and 4, has been added.
SymbolicPowers, a package by Eloisa Grifo for calculations involving symbolic powers, has been added.
TestIdeals, a package by Alberto F. Boix, Juliette Bruce, Drew Ellingson, Daniel Hernandez, Zhibek Kadyrsizova, Mordechai Katzman, Sara Malec, Matthew Mastroeni, Maral Mostafazadehfard, Marcus Robinson, Karl Schwede, Dan Smolkin, Pedro Teixeira, and Emily Witt for calculations of singularities in positive characteristic, has been added.
Topcom, a package by Mike Stillman that provides an interface to a small part of topcom, has been added.
TriangularSets, a package by Diego Cifuentes for triangular decomposition of ideals, has been added.
Tropical, a package by Kathlen Kohn, Sara Lamboglia, Diane Maclagan, Benjamin Smith, Jeff Sommars, Paolo Tripoli, Magdalena Zajaczkowska, and Magdalena Zajaczkowska for computations in tropical geometry, has been added.
improved packages:
The package CompleteIntersectionResolutions includes now the analysis of resolutions over complete intersections, and computations of the special resolutions of modules over complete intersections that were described by Eisenbud and Peeva in various papers.
The package ReesAlgebra has been improved: Corrected and completed the documentation and cleaned up code; added functionality having to do with options for computing saturation (used in the basic routines); added functionality of the 'Jacobian dual' method. Submitted JSAG article explaining the package.
The package K3Carpets includes now facilities for computing with K3carpets and their generalization, the correspondence scrolls, and using the Schreyer resolution and Schreyer naming of syzygies to determine in which characteristics they have behavior other than that corresponding to Green's conjecture. The computations are used in a forthcoming preprint by Eisenbud and Schreyer.
LocalRings has been rewritten by Mahrud Sayrafi and Mike Stillman. Functions from the old version are still available. The new package extends various primary functions to work over local rings with respect to prime ideals. These functions include syz, res, trim, mingens, minimalPresentation, symbol //, inducedMap, symbol :, saturate, annihilate. The function hilbertSamuelFunction for modules over local rings, optionally given a parameter ideal, has been added.
Cremona has been updated from version 3.9.1 to version 4.2. The class 'RationalMap' has been improved; in particular, this affects the way how the objects of the class are displayed. Support has been added for rational maps whose source is a subvariety of a product of projective spaces. For instance 'graph(RationalMap)' returns a pair of such maps. 'composeRationalMap(rationalMap,RationalMap)' has been replaced by 'rationalMap * RationalMap' 'invertBirMap' has been replaced by 'inverseMap' 'kernelComponent(RingMap,ZZ)' has been replaced by 'kernel(RingMap,ZZ)'
Resultants has been updated from version 1.0 to 1.2. 'CayleyTrick' has been changed and replaced by 'cayleyTrick' 'ChowEquations' has been replaced by 'chowEquations' 'ChowForm' has been replaced by 'chowForm' 'Discriminant' has been replaced by 'discriminant' 'Dual' has been replaced by 'dualVariety' 'Resultant' has been replaced by 'resultant' 'Xresultant(Ideal)' has been removed: use 'fromPluckerToStiefel dualize ChowForm I' instead The methods 'affineDiscriminant', 'affineResultant', 'hurwitzForm', 'macaulayFormula' has bees added.
The package TorAlgebra replaces the package CodepthThree. In addition to the functionality of CodepthThree, the new package now also implements the classification scheme (due to Kustin and Miller) for Gorenstein rings of codepth 4. Moreover, the package recognizes complete intersection, Gorenstein, and Golod rings of any codepth via the functions isCI, isGorenstein, and isGolod.
The package Divisor has numerous changes to core methods to make them compatible with Macaulay2 standards and conventions (including renaming many methods). Documentation is also improved throughout. Additional functionality has also been added (for example, checking if a divisor is very ample).
functionality added or improved:
The function localRing, for localizing a polynomial ring at a prime ideal, has been added.
The function length(Module) now can compute length of Artinian modules over local rings.
The function newPackage now takes two new options: OptionalComponentsPresent tells whether all optional external components of the package are present on the system, and UseCachedExampleOutput tells whether to use the cached example output files. This will be useful for packages that use external programs that are not always present, so they can seize the opportunity to rerun examples when the external programs are present and give no error when the external programs are absent.
functionality changed:
The format for multi-line (un-nested) block comments has been changed from {* ... *} to -* ... *- so Emacs can colorize the comments correctly. The (deprecated) old style will be recognized by M2 for a while.
The source of this document is in Macaulay2Doc/changes.m2:1373:0.