v0.3.0

Sequences now use the multiplicative notation of the literature, and the
documentation follows its terminology. Breaking changes take effect without a
deprecation period.

Breaking changes

• Sequences are written multiplicatively. S(g, h, ...) constructs the
  sequence g·h·…, S * T is the product, S ** k a power, S / T is
  S·T⁻¹ for a divisor T of S, and -S negates every term.
  S.from_terms(iterable) builds a sequence from an iterable, and
  math.prod() multiplies sequences. Removed: S([...]), +, -, integer
  *, and sum() support.
• AdditiveSequence.total() is renamed to sum().
• Symmetry keywords follow one rule. Queries whose answer depends on the group
  take group=, which defaults to the space's automorphism group: the
  catalogue orbit methods, AnchoredCanonicalizer (whose group is now
  optional), and the sequence orbit methods, where group= replaces action=
  and also accepts an AutomorphismGroup. Queries that use symmetry only to
  save work take symmetry=True|False|AutomorphismGroup: the zero-sum
  constants (default True) and FactorizationCache,
  AdditiveSequenceSpace.factorization_cache() and
  FactorizationCache.from_jsonl() (default False, replacing group=).
• AdditiveSequence.orbit() returns the orbit sorted, not in breadth-first
  order.
• Factorization queries raise ValueError when an explicit Davenport bound or
  a supplied atom catalogue provably cannot factor a zero-sum sequence, instead
  of returning empty results. Queries for a single length are unchanged.
• FactorizationCache.statistics is a property returning a
  FactorizationCacheStatistics dataclass instead of a method returning a
  dict. clear() now also resets the counters.
• AutomorphismGroup finds the identity among Automorphism elements or, when
  compose is given, as the idempotent element; otherwise identity= is
  required and its absence raises TypeError.
• Short reprs: sequences display as their product, groups and spaces by
  their construction, e.g. FiniteAdditiveGroup.cyclic_product(2, 4).
• Length caps and exponents reject booleans and other non-integers.
• The tutorial is a marimo notebook (notebooks/tutorial.py);
  notebooks/tutorial.ipynb and the Binder setup are removed, and the
  tutorial extra installs marimo and Matplotlib. Development tools moved
  from the dev extra to a dev dependency group
  (pip install --group dev).

Added

• Exact zero-sum constants: zero_sum_constant (with extremal sequences),
  davenport_constant, erdos_ginzburg_ziv_constant, eta_constant, and
  exponent, with symmetry reduction.
• The Davenport bound of a sequence space is optional. Without one, a
  certified bound is derived without an exhaustive search, using exact
  formulas where they apply; exact values are cached and shared between
  spaces over the same group.
• FiniteAdditiveGroup.order(), element_order(), exponent(), and
  negate().
• Groups, spaces, sequences, and catalogues can be pickled; sequences sent to
  worker processes compare equal to the caller's.
• Orbit methods use an automorphism group supplied by the parent when it has
  no explicit generators.
• FactorizationCache.from_jsonl() accepts canonicalize= and loads files
  saved with any symmetry setting.
• FactorizationStatistics and FactorizationCacheStatistics are exported.
• Documentation at https://zero-sum-sequences.readthedocs.io/, with
  definitions, an API reference, and the tutorial, runnable in the browser.
• Python 3.15 is tested.

Changed

• Maximum-only factorization queries use less memory.
• NetworkX is imported only when a factorization graph is requested.
• Sage is probed only for Sage parents, and unavailable symmetry is resolved
  once per space.

Fixed

• Parents whose zero() returns a non-canonical label give correct sums and
  zero-sum tests.

Full changelog: https://zero-sum-sequences.readthedocs.io/en/latest/changelog.html