SageManifolds metaticket 2

[egourgoulhon]

This metaticket collects tickets related to manifolds in Sage 9.3 or higher. For the initial implementation of manifolds in Sage up to version 9.2, see the metaticket 1: #18528.

The works listed here result from the ​SageManifolds project, developed by the following ​authors.

Generic

• #30139: Metaticket about manifold code improvement
• #30116: Replace __eq__ by _richcmp_ for manifolds
• #30473: Unicode art for sage.manifolds
• #30554: Metaticket: Deprecated features
• #30189: Metaticket: Add examples to manifold catalog
• #30799: Add folder for manifold examples (merged in Sage 9.3.beta0)
• #31202: Fix some typos in src/sage/manifolds/ (merged in Sage 9.3.beta9)
• #31241; Forgetful functors for manifold objects
• #31704: Remove Python 2 compatibility from manifolds

Algebraic part

• #28813: Enhance symmetry handling for tensors
• #29099: Extension of admissible indices conventions for tensors with indices
• #29619: Sparse iterator for tensor components
• #29820: Compacting the display of tensor product
• #29796: Parallelization of wedge product
• #30095: sage.tensor.modules: Add SymPowerFreeModule
• #30096: sage.tensor.modules: Add backends using TensorFlow Core and PyTorch:
• #30164: Add category FreeModules (without distinguished basis)
• #30174: Trivial coercion Modules(QQ)(FiniteRankFreeModule(QQ, 3)) fails (merged in Sage 9.3.beta8)
• #30229: Submodules of TensorFreeModule defined by the symmetries of a Components object
• #30235: Add construction methods to FiniteRankFreeModule and CombinatorialFreeModule
• #30241: New implementation class FiniteRankDualFreeModule
• #30242: Make ExtPowerFreeModule a quotient of TensorFreeModule
• #30245: FreeModuleAutomorphism should not inherit from FreeModuleTensor
• #30244: Use _matmul_ operator (@)
• #30276: Phased permutation groups
• #30302: Arithmetic on tensor module elements, manifold objects: always return a copy
• #30307: Refactor Components into parent & element
• #31276: Tensor product method for FiniteRankFreeModule
• #31946: _sympy_ methods for tensor component classes

Topological manifolds

• #24151: Improve simplifications in calculus on manifolds
• #24290: Make simplifications in SymPy calculus on manifolds rely on SymPy only
• #29775: Add a bit of typing to manifold code
• #30080: Manifolds with boundary
• #30232: Coercion/conversion SR to ScalarFieldAlgebra
• #30310: Immutability of chart functions (merged in Sage 9.3.beta9)
• #30311: Immutability of scalar fields II (merged in Sage 9.4.beta0)
• #31243: Stronger categories for manifold examples: connectedness (merged in Sage 9.3.beta7)
• #31371: Product of manifolds
• #31654: Equip scalar fields with copy_from method (merged in Sage 9.4.beta1)
• #31674: Make open subsets of immersed/embedded submanifolds immersed/embedded submanifolds (merged in Sage 9.4.beta1)
• #31677: Open subsets of arbitrary subsets of manifolds (merged in Sage 9.4.beta1)
• #31685: ContinuousMap.image: if map is an isomorphism and domain_subset is open, create a submanifold
• #31703: Sheaves on manifolds
• #31720: Manifold: Change some methods to generators
• #31771: Chart.subchart_poset, superchart_poset, Manifold.chart_poset
• #31883: Refine category of ScalarField
• #31894: Refine categories of Chart objects, add method codomain
• #31901: Chart: UniqueRepresentation fixes
• #31923: The inverse of the inverse should be self in CoordChange

Manifold subsets

• #31740 Meta-ticket: Families, posets, complexes of manifold subsets
• #30263: declare_union yields wrong results
• #31644: Topological closure of manifold subsets, embedded submanifolds
• #31653: Images of continuous maps and embedded submanifolds as manifold subsets (merged in Sage 9.4.beta1)
• #31675: Plotting subsets of real manifolds
• #31680: Poset of manifold subsets
• #31682: Add _test_... methods that check invariants of subset relations
• #31718: ManifoldSubset: Change some methods to generators

Differentiable manifolds

• #28629: Automorphism fields: remove SR enforcement when computing the inverse
• #28640: Vector-valued forms:
• #27492: Bug in parallelized computations involving symbolic functions
• #29234: Inheritance structure: tensor fields as sections of vector bundles
• #29581: New algorithm for characteristic classes
• #30211: Characteristic classes: sequences (merged in Sage 9.4.beta0)
• #30261: Immutability for manifold objects
• #30272: Mixed forms: set_comp, comp
• #30284: Immutability of bundle connections (merged in Sage 9.3.rc0)
• #30495: sage.manifolds: Connect to Pymanopt
• #30714: Tensor arithmetics on minimal amount of domains
• #30781: Covariant derivatives along smooth maps
• #30830: Subintervals of OpenInterval and UniqueRepresentation (merged in Sage 9.3.beta2)
• #30832: Connect RealSet to sage.manifolds
• #31215: Documentation of item assignment behavior for bundle connections (merged in Sage 9.3.beta7)
• #31249: Grassmann manifolds
• #31255: Follow up: Mutability of sections and tensor fields (merged in Sage 9.3.beta7)
• #31273: Remove deprecated form input for bundle connections (merged in Sage 9.3.beta7)
• #31316: Method subs() ineffective on tensor fields
• #31323: Make self-diffeomorphisms default (merged in Sage 9.3.beta9)
• #31324: Circle doesn't have an orientation
• #31609: Add method tangent_vector() to differentiable manifolds (merged in Sage 9.4.beta1)
• #31617: Provide 3-sphere with additional features
• #31633: Simplify VectorField.__call__ (merged in Sage 9.4.beta1)
• #31658: Speeding-up copy method for tensor fields (merged in Sage 9.4.beta1)
• #31678: DifferentiableManifold.open_subset: update vector frames and change of frames
• #31691: Turn mixed form algebra into de Rham complex (and add de Rham cohomology) (merged in Sage 9.4.beta1)
• #31692: Refactor display behavior of mixed forms (merged in Sage 9.4.beta1)
• #31706: Immutability for mixed forms
• #31784: Mixed form name bug for pullback bundle
• #31904: Pullback silently fails in some cases with multiple charts

Pseudo-Riemannian manifolds

• #25457: Declaring a metric along with its components
• #25500: Energy momentum tensor, Einstein tensor and Einstein space-time
• #30804: Add standard sphere to manifold catalog (merged in Sage 9.3.beta2)
• #30824: More flexible coordinate treatment for EuclideanSpace
• #31322: Use ambient metric by default in hodge_dual (merged in Sage 9.3.beta9)
• #31707: Manifold of piecewise linear functions with k marked breakpoints
• #31747: Add spherical coordinates with equator-based latitude
• #31777: manifolds.Sphere: Add barycentric coordinates of spherical triangles / Whitney forms
• #31781: Unusable metric on spheres from the manifold catalog
• #31813: Add support for tangent_vector_eval_at for geodesics on manifolds integrated over multiple charts

Poisson manifolds

• #30362: Add symplectic structures

Complex and almost complex manifolds

• #18786: almost complex structures through Hodge structures