mutation

the mutation domain introduces structured, stateful change into playback materials. while variation governs one-time transformations, mutation operates over time, modifying a working copy derived from a static template. this separation allows material to evolve gradually while preserving deterministic control. each mutation form accumulates change deterministically and supports optional reset mechanisms to re-anchor the evolution. this enables behaviors such as incremental jitter, cyclic transformations, controlled randomness, and template switching - all precomputed, reproducible, and structurally aware.

each form maps parameters a and b ∈ [0,1] to meaningful musical behaviors. forms are irreducible, additive, and non-overlapping:

• accumulated drift

  • behavior: adds micro-perturbations to values on each iteration, creating smooth or noisy drift.
  • analogy: gradual detuning or rhythmic wobble
  • a: step size per mutation
  • b: max drift range (clamped)

• rotating sequence

  • behavior: applies a cyclic shift to sequence elements each time the motif repeats.
  • analogy: conveyor belt rotation
  • a: elements shifted per iteration
  • b: rotation bias (0 = forward, 1 = backward)

• segment swap

  • behavior: exchanges two sub-sections of the sequence at regular intervals.
  • analogy: shuffling cards
  • a: swap size (as fraction of sequence length)
  • b: swap frequency

• value mapping

  • behavior: applies a deterministic remapping function or table to all values in the sequence.
  • analogy: function composition
  • a: mapping index (selects function or table)
  • b: mapping intensity (0 = original, 1 = full remap)

• reset clock

  • behavior: reverts the mutated sequence to the original template periodically.
  • analogy: return to home base
  • a: reset interval (as proportion of global time scale)
  • b: reset depth (0 = full reset, 1 = minimal reset)

• template switch

  • behavior: changes the base template that the working copy mutates from, at defined moments.
  • analogy: changing stylistic source
  • a: switch timing (0 = frequent, 1 = rare)
  • b: blend between old and new templates

• accumulated drift

  • a: step magnitude
  • b: clamp threshold

• rotating sequence

  • a: shift amount (elements per repeat)
  • b: direction bias

• segment swap

  • a: swap size
  • b: swap occurrence rate

• value mapping

  • a: selects remap function or table
  • b: interpolation amount

• reset clock

  • a: time between resets
  • b: extent of reset

• template switch

  • a: how often switching occurs
  • b: degree of morphing between templates

• coverage: together, these forms span the essential mutation strategies: accumulation, cycling, recombination, remapping, re-anchoring, and source transition.
• irreducibility: no form is derivable from others; each represents a distinct mode of temporal change.
• compositional utility: provides rich, structured evolution without runtime logic or unpredictability.
• parametric transparency: each control has clear musical consequences.
• functional alignment: conceptually aligned with map, fold, unfold, and state transitions from functional programming.

• one-time transformations: handled in the variation domain.
• conditional or reactive resets: those require runtime logic, which is outside the system scope.
• stochastic accumulation with unbounded entropy: only bounded, deterministic processes are allowed.
• timbre-level mutations: these belong in the decorators, dynamics, or timbre domains.
• spatial transformations: addressed in the spatial layer.

the mutation domain provides a formal framework for deterministic sequence evolution. through accumulation, reset, and controlled remapping, it enables gradual transformation while preserving structural anchoring. its six forms are compact, expressive, and fully resolved at design time - making mutation a cornerstone for generative, non-repetitive structure within the deterministic compositional space of 声音.