# changes, 1.12

• new packages:
• Seminormalization, a package by Bernard Serbinowski and Karl Schwede for computing seminormalization of rings, has been added.
• CoincidentRootLoci, a package by M. C. Brambilla and G. Staglianò for computations with coincident root loci, has been added.
• RelativeCanonicalResolution, a package by Christian Bopp and Michael Hoff for computation of the relative canonical resolution for g-nodal canonical curves with a fixed $g^1_k$, has been added.
• RandomCurvesOverVerySmallFiniteFields, a package by Christian Bopp and Frank-Olaf Schreyer for computation of general canonical curves of genus $\le 15$ over fields with small characteristic, has been added.
• StronglyStableIdeals, a package by Davide Alberelli and Paolo Lella for studying strongly stable ideals related to Hilbert polynomials, has been added.
• SLnEquivariantMatrices, a package by Ada Boralevi, Daniele Faenzi and Paolo Lella for computations related to the paper "A construction of equivariant bundles on the space of symmetric forms", has been added.
• CorrespondenceScrolls, a package by David Eisenbud, Frank-Olaf Schreyer, and Alessio Sammartano, to compute and analyze examples of correspondence scrolls, has been added.
• NCAlgebra, a package by Frank Moore, Andrew Conner, and Courtney Gibbons, implementing data types for noncommutative algebras, has been added.
• SpaceCurves, a package by Frank Schreyer, Mike Stillman, and Mengyuan Zhang, for generation of space curves, has been added.
• ExteriorIdeals, a package by Marilena Crupi and Luca Amata for manipulating monomial ideals over exterior algebras, has been added.
• packages that have been published and certified:
• Resultants, a package by Giovanni Staglianò for resultants and discriminants for multivariate polynomials, has been published.
• SpaceCurves, a package by Frank Schreyer, Mike Stillman, and Mengyuan Zhang, for generation of space curves, has been published.
• ReesAlgebra, a package by David Eisenbud, Amelia Taylor, and Sorin Popescu for computations with Rees algebras, has been published.
• Cremona, a package by Giovanni Staglianò for computations for rational maps between projective varieties, has been published.
• ExteriorIdeals, a package by Marilena Crupi and Luca Amata for manipulating monomial ideals over exterior algebras, has been published.
• improved packages:
• The package VersalDeformations has had a bug fixed. The lifting algorithm would give an error or incorrect output if the tangent cone for the obstruction equations wasn't generated by the lowest order terms of the obstruction equations. This has been remedied by actually calculating the tangent cone, and making appropriate adjustments to the algorithm.
• The package TateOnProducts has been improved. The package implements the method of Tate resolutions, for computing cohomology of sheaves on products of projective spaces, and also the pushforward complex of a sheaf under a map from a variety to a projective space. Tate resolutions on single projective spaces were treated in the package BGG, but the case of a product of projective spaces is much more subtle, since no term of the full Tate resolution is finitely generated.
• functionality added or improved:
• The function about has been added. It allows one to search the documentation of all the packages that have been installed, optionally searching the contents, in addition to the keys. For example, the command help about X will display all the documentation about X.
• The class NumberedVerticalList has been added. It's a new type of vertical list (see VerticalList) that is also printed vertically, but with numbered entries, for ease of referring to them.
• The option AbsoluteLinks to installPackage has been removed. Better logic is now used internally, producing relative links only between files installed under the same prefix.
• The layout of files into directories used by installPackage has been simplified, so it may be a good idea to reinstall any packages you have installed. See Layout.
• Each directory listed in prefixPath now has its own layout, which is detected at runtime. See Layout.
• Functionality for fast nonminimal free resolutions, FastNonminimal has a number of bug fixes and improvements: (1) it now works for input modules, not just ideals (there was a monomial order mismatch which would often cause it to fail), (2) multigraded and inhomogeneous ideals/modules are allowed, (3) this function works over the exterior algebra as well (it has always done so, but that was not always realized), (4) it is possible to have M2 use an already created Groebner basis, instead of recomputing one. Use Strategy=>5 in the resolution command, to tell the command that the provided ideal has generators which already form a Groebner basis, not necessarily a reduced Groebner basis, or a quotient module, whose presentation matrix forms a Groebner basis. If the input is not, then this function can give incorrect answers or fail. See FastNonminimal for details and examples.
• New types MethodFunctionSingle and MethodFunctionBinary were introduced to serve as classes of method functions with a single argument, such as code, and of associative method functions based on methods with two arguments, such as gcd, from other compiled functions.
• We have removed the feature where typing an extra empty line ends multiline input in a terminal window or emacs buffer. This will make it easier to feed input from a file into the interpreter with F-11 and encounter the same behavior, since in files we have permit empty lines. This change was requested at our Leipzig workshop, with Q2 at https://github.com/Macaulay2/Workshop-2018-Leipzig/wiki/Q&A-Thursday being the question that prompted the discussion.
• commits, issues, and pull requests on github
• See closed 1.12 issues, for the issues and pull requests incorporated into 1.12.
• See 1.12 commits for complete information about all changes to the code incorporated into 1.12.