Frequently Asked Questions

Contents

Frequently Asked Questions#

This FAQ explains the algorithm, the objects studied by its convergence analysis, and its geometric and physical interpretations. The volume proves finite-particle QSD convergence, population-uniform functional inequalities under structural hypotheses, and mean-field well-posedness and attraction in an explicit regime. Start with the question that interests you, then follow the linked definition or chapter. An answer about one transition rule applies to another only when the relevant hypotheses have been checked.

The volume introduction gives the reading order. The latent specification separates identities of the update rule from the additional assumptions needed for long-time behavior and population limits.

Familiar question

Where it enters this volume

How is a search population updated?

Algorithms and foundations

Does the population relax to a limiting law?

Finite-particle convergence

What can a density approximate?

Mean-field limits and equilibrium

How accurate is a finite computation?

Entropy, regularity, and bounds

What does a recorded interaction graph represent?

Fractal Set and continuum limits

How are field observables defined and tested?

Fields and experiments

Algorithm fundamentals#

Why give a walker velocity as well as position?#

Velocity is part of the kinetic models studied here. It supports persistent motion, friction, a momentum thermostat, and velocity-dependent interactions. The chosen companion distance can also compare velocities. These are modeling choices with consequences for the transition kernel. Position-only algorithms are possible, but their analysis concerns a different process.

See the single-particle analysis and Definition 494. In the latent specification, coordinate subtraction of velocities is chart-dependent; using a metric in the kinetic step does not itself make that subtraction intrinsic.

Why sample companions with a soft kernel?#

A soft kernel assigns positive probability to each eligible companion in exact arithmetic. Nearby companions can be favored without making the choice completely deterministic. On a set with bounded algorithmic diameter, one can bound these probabilities uniformly from below; see Lemma 102.

That bound concerns a draw from the current finite list. Accessibility and mixing of the full swarm also depend on cloning, motion, noise, and killing. On an unbounded state space, the finite-list bound need not have a positive uniform floor over all swarm configurations. Hard neighbor selection and truncated kernels require their own analysis.

What do reward and diversity contribute to fitness?#

Reward scores task performance; diversity measures separation using the chosen companion rule. The regularized product of their transformed values lets both channels influence cloning. The exponents and normalizations determine their relative effect.

A diversity channel can oppose concentration, but a lower bound on population spread requires an estimate for the dynamics. Setting one exponent to zero removes that channel’s contribution; it does not by itself imply immediate collapse or a pure random walk. Neither a Gibbs law nor an exact power of reward follows from the product formula alone. See Definition 496.

Is sampled fitness the same as expected fitness?#

At a fixed swarm state, fitness can still depend on the randomly drawn distance companion. Holding that assignment fixed gives the sampled-fitness derivative. Differentiating its expectation also differentiates the companion probabilities. The volume proves regularity for both quantities, as well as for the separate surrogate obtained by inserting expected measurements into the fitness formula; see Theorem 271.

These three functions generally have different values. The distinction survives a population limit when each walker still draws one companion: taking a nonlinear function and taking an expectation need not commute. The limiting model must preserve the algorithm’s order of sampling and evaluation. See Remark 118.

Is smoothness proved for the actual greedy companion algorithm?#

Yes. Lemma 223 proves a derivative bound for the actual sequential greedy history law, with a pivot rule independent of the continuous state. The proof sums over all pairing histories. Once the moving walker has been paired, it stops influencing the remaining choices; this closes an induction whose constant does not grow with the number of pairs.

Combining that history bound with the normalized measurement and fitness calculus proves smoothness of the full expected sampled fitness. Under fixed positive scales and regularizers, bounded pair distances, and uniform analytic reward bounds, Theorem 272 gives the factorial estimate \(\|D^nF\|\le C_FB_F^nn!\), with \(C_F,B_F\) independent of population size. It applies to derivatives in a specified walker-position block on a fixed alive, candidate, and branch stratum. Smooth inputs give smoothness; the stronger factorial hypotheses give analyticity.

Independent sampling, idealized matching, and greedy matching each have a proved regularity calculation. Their probability laws differ, as the four-walker example in Remark 205 shows. Smoothness therefore supplies coefficient estimates for each model without identifying their dynamics. On unbounded families, use the theorem’s normalized derivative-ratio and joint-law majorants; the bounded-distance argument does not impose compactness on every algorithmic model.

Why keep the number of walker slots fixed?#

A fixed number of slots makes the computational budget and swarm state space explicit. Cloning reallocates those slots among states. The number currently marked alive can still change during an update.

Variable-population methods are mathematically possible. They require a state space and update rule that account for population changes, followed by estimates for that process. A fixed population is a choice of this algorithm family, rather than a general requirement of transport geometry or mean-field analysis.

What happens when a walker is marked dead?#

The alive mask and replacement rule specify its treatment. In the nondegenerate latent update, a dead walker draws an alive companion and is assigned a cloning update. Jitter can subsequently place the copied position outside the alive region; the next mask evaluation detects that outcome.

The stopping rule matters. The mathematical latent specification stops when fewer than two walkers are alive. The implementation discussed there allows a lone survivor to select itself. These are different kernels at that boundary. A dead slot inside a surviving swarm is also distinct from the cemetery state of the entire killed process. See Definition 495 and Definition 497.

Cloning and kinetic dynamics#

What does the direction of cloning establish?#

For the stored fitness values used in a step, a positive cloning score directs replacement toward a fitter companion. The frozen-score alignment identity is proved in Lemma 97.

That identity concerns copied scores. After jitter, collision, motion, and a new fitness measurement, both the walker states and the population statistics may have changed. A Lyapunov inequality for the complete transition needs estimates for those operations as well. Directed selection alone gives no such inequality.

Does asymmetric cloning imply fermionic statistics?#

The sign of a fitness difference records which direction of copying is favored. The connection to fermionic operators is made through the law and transition operator of the complete algorithm. In Theorem 339, centered square-integrable observables of the stationary conservative process form the one-particle space. Exterior multiplication creates an observable mode, contraction removes it, and their canonical anticommutation relations follow by an explicit calculation. The lifted transition has a one-particle vacuum matrix element equal to the connected covariance measured in that same stochastic process. For a finite run away from equilibrium, Proposition 238 gives the corresponding construction from the joint law at two recorded times, including the empirical law used to compute sample covariances; stationarity is unnecessary for that identity.

What do the higher-particle sectors represent? Take independent copies of the complete process and antisymmetrize their observable amplitudes. Theorem 340 identifies the resulting centered antisymmetric replica sector isometrically with the exterior space and intertwines their evolution. Its propagators are determinants of the one-particle propagators, with the exchange sign fixed by antisymmetrization. Thus the reconstruction supplies both the fermionic algebra and an exact stochastic meaning for its matrix elements.

The copies here are entire swarms, each retaining its internal interactions. They are not the interacting walkers within one recorded swarm. Likewise, Proposition 239 proves why scalar multiplication observables cannot themselves be identified multiplicatively with the full fermionic operator algebra. These distinctions specify precisely which statistics the reconstruction computes.

What does the inelastic collision conserve?#

Within one collision group with unit coordinate masses, the update preserves the mean velocity and shrinks deviations from it by the restitution coefficient. The resulting momentum and relative-energy identities have direct proofs in Lemma 96.

For disjoint groups, these identities sum over the population. When groups write to overlapping recipients using the original velocities, global conservation needs separate analysis of those writes. On a variable metric, summing coordinate velocities at different positions also requires care before interpreting the sum as physical momentum. Momentum conservation alone implies neither symplecticity nor convergence to equilibrium.

Can the whole swarm become extinct?#

Yes, when the specified killing rule allows extinction. A replacement rule that uses surviving companions needs an eligible source. A lower bound on companion probabilities cannot supply one when that set is empty. The latent mathematical variant also has the stricter stopping rule described above.

Restarting after termination defines an additional transition. Its stationary law must be analyzed for that restarted process. Conditioning a killed process on survival is a different operation. See Definition 505.

What does the Boris–BAOAB splitting guarantee?#

The splitting separates force kicks, position updates, a thermostat, and any rotation. Some individual steps admit exact identities: the frozen-metric Boris rotation preserves its kinetic norm, and the thermostat has explicit conditional moments. See Lemma 100 and Lemma 101.

The stochastic, dissipative, capped full update requires its own accuracy and stability analysis. In particular, the force coefficients in the displayed latent sequence must be compared with ordinary BAOAB before importing an integrator result; see Remark 114. Claims about invariant-measure bias also require the actual boundary rule, regularity, and target measure.

How do long-time, population, and continuum limits differ?#

At fixed population and step size, long-time analysis studies the repeated transition kernel. A population limit changes the number of walkers and studies marginals or empirical measures. A small-step limit changes the discretization in time. A geometric continuum limit additionally changes the graph or kernel resolution.

Each limit needs its own estimates, and exchanging their order requires uniformity. See mean-field analysis and continuum conditions.

Why use Wasserstein–Fisher–Rao or Hellinger–Kantorovich geometry?#

These geometries describe motion together with local gain or loss of mass. Fixed walker slots are compatible with local selection: replacing one alive walker redistributes the empirical measure, while its total alive mass changes only through the specified death and revival bookkeeping.

The HK chapter proves a direct convergence route. It separates the error in square roots of total masses from the Hellinger error of normalized shapes. Relative entropy controls the latter, and the transportation inequality controls the Wasserstein term; see Theorem 252. This gives a quantitative bound for the chapter’s additive mass-and-shape diagnostic without a global density-ratio assumption. The canonical dynamic HK metric has its own normalization and bounds.

Apply these comparisons to probability laws or explicitly smoothed empirical measures. An atomic empirical cloud and a diffuse density are mutually singular in Hellinger distance. See Remark 197 and WFR geometry in Volume I.

Convergence, constraints, and error bounds#

Which parameter constraints establish convergence?#

The composed analysis combines cloning and kinetic drift estimates and proves QSD convergence for the actual killed transition under its survival and comparison hypotheses. In particular, Theorem 209 gives a unique QSD and geometric convergence when a surviving block of the kernel has the stated two-sided measure bound.

Use the parameter chapter to connect confinement, forces, noise, companion probabilities, regularization, and step size to the estimates in that theorem. A block comparison constant, an entropy dissipation rate, and a variance diagnostic are different quantities. The proofs specify which combination yields each conclusion and whether its constant is uniform in population size.

Can the original algorithm-specific results use classical tools?#

Yes; the volume supplies direct proofs. The cloning chapter establishes its selection, variance, and boundary estimates, and the kinetic chapter develops confinement and motion estimates. Their composition is analyzed at the level of the specified swarm transition in Theorem 209.

The same approach continues through the book: normalized derivative calculus proves coefficient regularity, functional inequalities control entropy and fluctuations, and gain-loss estimates give a well-posed mean-field equation. Each implication has a complete argument with its model and parameter hypotheses stated. The latent specification links these results to the update quantities; its abstract Proposition 123 is one summary criterion, alongside the detailed component and composition proofs.

Are mean-field existence, uniqueness, and convergence proved?#

Yes, for the specified gain-loss equation. Under its positive, mass-preserving kinetic semigroup and bounded Lipschitz gain-loss assumptions, thm-chaos-mild-wellposedness constructs a unique global positive probability-density solution. The proof uses a damped integral equation that preserves positivity and mass at every iteration. Kinetic smoothing extends it to singular initial laws in cor-chaos-measure-initial-data. Kernels normalized by alive mass use the positive-alive estimates in rem-chaos-positive-alive-localization for continuation.

There is also a proved stationary-state and attraction theorem. If the kinetic semigroup contracts zero-mass differences with bound \(Ke^{-at}\) and the reaction has Lipschitz constant \(L_{\mathcal R}\), the regime \(b=a-KL_{\mathcal R}>0\) gives a unique stationary law and exponential attraction at rate \(b\); see thm-uniqueness-uniqueness-stationary-solution. This condition compares the rate at which motion removes differences with the rate at which the nonlinear reaction can amplify them.

The population-limit step is proved separately. Theorem 236 combines finite-time consistency, vanishing scaled extinction probability, and global attraction to obtain stationary propagation of chaos. Corollary 75 gives the other route through joint-law concentration and stationary-equation identification. These results retain the actual collision, sampling, and time-scaling conditions needed to connect a finite swarm to that mean-field equation.

Is a QSD the same as an invariant measure?#

An invariant probability measure is unchanged by a conservative transition. A QSD is unchanged by a killed transition after conditioning on survival and renormalizing. Existence of either measure concerns the particular kernel and state space being studied.

A full-swarm QSD, a one-particle marginal of that QSD, a killed single-particle law, and a mean-field stationary density are distinct objects. An exact Gibbs formula or a power-law expression in reward requires a separate identification of the appropriate law. See Remark 120 and discrete QSD structure.

Does decreasing population variance prove Wasserstein contraction?#

Population variance measures spread within one swarm. Wasserstein contraction compares two evolving probability laws. Two swarms can each have zero positional variance while being concentrated at different locations. Their variance says nothing about the distance between them.

A contraction proof needs a coupling or another estimate that controls that distance for the full transition. Likewise, an observed cloning frequency is a frequency, rather than a positional contraction rate. See Wasserstein control and Remark 115.

Is there a universal error proportional to the inverse square root of population size?#

For a smooth empirical average there is a proved population-uniform bound. If the actual joint law satisfies the full-gradient LSI of Corollary 94, then its Poincaré inequality gives \(\operatorname{Var}(N^{-1}\sum_i\varphi(Z_i))\le C_*L^2/N\) for an \(L\)-Lipschitz observable in the stated form domain; see Corollary 98. Thus its standard deviation is at most \(\sqrt{C_*}L/\sqrt N\), even though the walkers can be dependent.

Without that structural estimate, the exact variance includes every pair covariance. Exchangeability alone does not remove those terms. Discrete alive indicators also require a form controlling status changes, and an average over alive walkers includes its random denominator.

An empirical measure in Wasserstein distance has a separate sampling error, which depends on dimension and moment assumptions. Comparing an empirical average with a limiting density also includes marginal bias and finite-time relaxation. The quantitative bounds keep those contributions and entropy normalization explicit.

Where is the population-uniform logarithmic Sobolev inequality proved?#

Corollary 94 assembles four complete analytical routes for the specified continuous joint law: a product kinetic reference, a uniformly bounded whole-law density tilt of that reference, a uniform lower bound on the full joint potential Hessian, and an invariant law of a contractive additive-noise flow. Each route gives the same convention \(\operatorname{Ent}_{\pi_N}(f^2)\le2C_*\int\sum_i(|\nabla_{x_i}f|^2+ |\nabla_{v_i}f|^2)\,d\pi_N\), with \(C_*\) independent of \(N\).

The reference-measure proof includes nonconvex confining potentials on unbounded space; see Corollary 92 and Theorem 284. Tensorization retains the one-particle constant. Joint perturbation and contractive-flow arguments then treat the corresponding interacting families. For an invariant swarm law or a QSD, use the structural criterion satisfied by that particular law. A law with discrete status variables also needs the status entropy term stated in the chapter.

The full gradient matters. A function depending only on positions has zero velocity gradient, so velocity dissipation alone cannot control its static entropy. Hypocoercivity uses transport to connect those position variations to the directions in which noise acts.

Does mixing automatically give an entropy decay rate?#

The volume proves entropy decay by combining a functional inequality with the full evolution equation. In Theorem 285, the kinetic calculation uses a modified entropy consisting of relative entropy plus a positive quadratic form in position and velocity derivatives. Its mixed terms transfer velocity dissipation to position variations. The resulting differential inequality gives an explicit exponential rate.

For the complete normalized swarm evolution, Theorem 287 gives \(H(t)\le\Phi(t)\le e^{-rt}\Phi(0)\) with \(r=\delta/(C/2+g_+)\), where \(C\) is the actual joint-law LSI constant, \(g_+\) bounds the modification matrix, and \(\delta\) is the full dissipation constant. Uniform bounds on these quantities give a rate independent of \(N\). The kinetic and common-target cloning cases have explicit dissipation proofs.

Killing is included in the normalized equation. Proposition 178 proves the exact diffusion-jump entropy identity with the survival-normalization term; the boundary version retains the outgoing flux. Thus a QSD is handled through its eigenmeasure identity. For a finite-step algorithm, Lemma 181 propagates the proved one-step entropy defect and its error floor. A mixing estimate in another metric becomes part of this argument only through an established comparison.

The Fractal Set and continuum geometry#

Why record interactions as a directed complex?#

An interaction involves a companion, a receiving walker before an update, and that walker afterward. The Fractal Set records these incidences as interaction triangles, with distinct temporal, interaction, and attribution edges. This is a specified organization of the recorded data. It does not determine the dimension of a continuum spacetime.

Exact reconstruction depends on which states, random increments, parameters, and sampling times are stored. Consult the Fractal Set definition and compare its storage requirements with the available run history.

For fermionic reconstruction, the orientation also fixes which matrix entry describes a transfer from one recorded mode to another. Theorem 342 converts that directed matrix into creation-and-annihilation bilinears and calculates their action on exterior states. The edge weights specify the coefficients; the exterior construction specifies the exchange algebra. The correspondence with the actual stochastic transition is given separately, and explicitly, in Theorem 339.

How are fermionic operators constructed from recorded data?#

The reconstruction in Theorem 339 starts from observables and the transition of the stationary conservative algorithm. Its exterior operators obey the canonical anticommutation relations, and Theorem 340 identifies their evolution with the centered antisymmetric sector of independent algorithm replicas. Each replica retains the interactions among its walkers. The inner products and transition matrix elements are computed under the recorded law.

Do backward attribution edges imply backward causation?#

An attribution edge points from an output to an earlier input used in its update. Its direction records how to trace an influence. The update itself still uses the prescribed time order.

The causal order is defined using the selected forward-time relation, rather than every oriented edge of the interaction complex. Attribution edges can close loops used for geometric observables without becoming extra causal arrows.

In what sense is the record a causal set?#

Starting from a relation that strictly increases the discrete time index, its strict transitive closure is irreflexive and transitive. With finitely many walkers at each step, a bounded discrete-time interval contains finitely many recorded events. These facts support the order-theoretic construction.

A locally finite order alone does not identify a Lorentzian manifold, its metric, or a sampling law. Those require additional geometry. See causal-set constructions.

What is assumed when the walker record is used as a spatial sample?#

Walker locations can be dependent and nonuniform, and the estimates use their actual observation law. The joint LSI gives a direct way to control this dependence. For the smooth kernel estimator in Lemma 298, the resulting Poincaré inequality gives variance at most \(C/(N\varepsilon^{D+4})\) under its derivative, density, and form domain conditions. The bandwidth scaling must make that bound tend to zero; the deterministic kernel bias is controlled separately.

This is stronger than applying a fixed-observable law of large numbers to a shrinking neighborhood. It tracks how derivatives grow as the bandwidth shrinks. The continuum conditions assemble these sampling, normalization, and geometric estimates for each specified continuum construction.

When is a continuum spacetime interpretation justified?#

Specify the candidate manifold, metric, causal neighborhoods, and correspondence with the discrete record. Then establish convergence of the distances, operators, or energies used in the interpretation under a compatible scaling regime.

Propagation of chaos concerns particle laws. It does not supply global hyperbolicity, a Lorentzian signature, or a continuum differential operator by itself. Unproved geometric identifications remain assumptions or conjectures in the resulting statement. See Part V.

Gauge constructions and physical claims#

How can I tell whether a proposed gauge symmetry is present?#

Specify the transformation of every variable, the observables it preserves, and its action on the transition or field dynamics. Then check the claimed invariance. A global change of basis and an independent change of frame at each node are different operations.

The precise formula matters. Adding a common constant to the stored fitness values generally changes the normalized cloning score through its denominator, even though their differences stay fixed. Thus a claimed fitness-shift symmetry must be checked for the actual update. See lattice field constructions and Definition 497.

Do the algorithm’s three mechanisms determine three gauge groups?#

The chapter constructs the representations explicitly. A phase fiber supplies \(U(1)\); a chosen Hermitian doublet with a determinant volume form supplies \(SU(2)\); and a chosen Hermitian color fiber with its determinant form supplies \(SU(n)\). The normalization and generator identities have direct proofs in Theorem 351 and Theorem 352. Their actions on separate tensor factors commute, giving the product representation in Corollary 121. Its faithful group divides out the subgroup acting trivially on the supplied matter representations.

Those fiber structures and comparison links are part of the field construction. The number of algorithmic mechanisms alone does not select them. The viscous force has a proved orthogonal covariance, while its nonlinear componentwise color encoding needs the representation map stated in the theorem. Relating the constructed gauge action to the swarm dynamics and measured physical couplings uses the realization and calibration conditions in the Standard Model chapter.

Can Wilson observables be defined on triangles?#

Given compatible link transports, one can compose them around a triangular loop. Under a gauge transformation, the based holonomy transforms by conjugation; its trace is invariant. The holonomy matrix itself is generally not invariant.

For noncommuting transports, combining neighboring loops requires compatible base points, order, and orientations. An action built from such loops then has its own weights and normalization. Convergence to a continuum Yang–Mills action requires a consistency and scaling argument for that construction. See Wilson-loop computation and Yang–Mills analysis.

Does choosing three latent dimensions establish the Standard Model?#

Choosing a three-dimensional space is a model input. Even when an \(SU(3)\) representation is constructed, identifying the Standard Model also requires its matter content, representations, dynamics, and observable predictions. A match of group names or dimensions establishes only that specific match.

The same caution applies to a proposed correspondence between latent dimension and the number of particle generations. That correspondence needs its own argument and evidence; it is not fixed by the dimension choice alone.

Do different companion ranges establish CP violation?#

Different companion ranges change the actual companion probabilities. To test CP symmetry, specify the transformation of the recorded variables and evaluate an observable that changes sign under it. As proved in Theorem 372, a nonzero expectation of that observable rules out invariance of the recorded law under the transformation. The expectation uses the complete update and its initial law.

What does the recorded ancestry determine?#

The parent map records which earlier event supplied a clone’s ancestry. Definition 720 uses this map to pull an episode observable back to its recorded parent. Applying it twice follows two ancestry steps. Repeated walker labels at different times remain distinct events, and the complete history retains their values and incidences.

Implementation and connections to the agent#

How does the Fractal Gas connect to Volume I?#

An agent can supply a learned state space, metric, model, or score in which a swarm searches. The swarm can supply candidate trajectories and measurements for planning or learning. This is a possible integration of the two volumes.

When learned quantities change during the run, the transition changes with them. Applying a fixed-kernel estimate then requires controlling that adaptation or including the additional variables in the analyzed state. See the Fragile Mechanics introduction and latent model.

What about distributed optimization or economic applications?#

A distributed application must specify the objective, communication pattern, work measurement, and incentive rules. Convergence of a particle algorithm addresses only the hypotheses and conclusions of its own model. Consensus and incentive properties require their own analysis.

Volume I’s economics chapter develops that separate application setting.

What determines the computational cost?#

Direct evaluation of all pairwise distances among \(N\) walkers in dimension \(d\) costs on the order of \(N^2d\) arithmetic operations. Materializing all pairwise weights uses quadratic storage; streaming or blocking changes the memory cost. Fitness, force, Hessian, environment, and recording costs must be counted as well.

Restricting companions to a local neighborhood changes the sampling law. Its accuracy and accessibility need analysis, especially when a theorem uses a positive probability for every eligible companion. GPU parallelism can reduce wall-clock time without changing the number of pairwise operations. Measure the configured implementation on the task of interest.

How do the constraints help with tuning?#

An explicit inequality relates parameters to a stated property. It can guide a choice when all quantities in the inequality are known or bounded in the application. A default configuration is a starting point for a particular implementation, rather than a universal feasible point for every objective.

Record the units, step size, noise, companion range, regularization, and stopping rule. Compare diagnostics with the estimates they actually measure. See parameter constraints and computational proxies.

How should I compare it with a gradient method or another population method?#

Specify the objective and the computational budget first. Compare methods using the same environment interactions or objective evaluations, and also report wall-clock time when computation differs. Distinguish finding a high-scoring state from sampling a specified probability law.

A population can explore several candidate regions, but superiority on a task is an empirical question. A gradient-based kinetic variant also uses derivatives; calling the whole algorithm gradient-free would omit that cost and requirement. See computation and experiments.

Interpretation, evidence, and mathematical status#

What does the name “Fractal Gas” imply?#

The name identifies the algorithm family and its connection to the Fractal Set record. The actual specification includes length and time scales: companion bandwidths, jitter, smoothing, and a time step. Exact scale invariance or a particular fractal dimension requires a separate statement and analysis.

Use the literature guide for historical sources and the algorithm introduction for the operational definition.

What kind of connection between optimization and physics is being studied?#

One can construct fields and geometric observables from an algorithm’s record, then study their algebra and dynamics. A claimed mathematical equivalence must specify the objects, maps, and properties preserved. A physical identification additionally concerns agreement with measurements and the range of that agreement.

Neither a visual resemblance nor a shared group name establishes the full connection. The field chapters provide the constructions to inspect; unproved parts remain conditional or conjectural.

What can experiments test?#

Experiments can test a specified prediction for a specified implementation and parameter regime. Examples include an update identity, a conditional relaxation curve, an observable’s population-size dependence, or a geometric estimator’s behavior under refinement. State the predicted quantity, sampling procedure, uncertainty, and calibration inputs before interpreting agreement.

A discrepancy can reveal a coding error, a violated hypothesis, an inaccurate approximation, or a false conjecture. Distinguishing these requires checking the model and measurement together. Agreement on finite runs supports the tested comparison; it is not a proof of a universal continuum or physical identification. See empirical studies and the calibration guide.

What does a successful coupling or mass fit establish?#

The calibration report solves a declared dictionary between physical targets, algorithmic parameters, and measured pair statistics. Its inversion is exact for the fixed inputs. A new simulation can change those statistics, so a self-consistent calibration also remeasures them and tests the resulting correlations. See the calibration report.

The active channel definitions matter before fitting. Under the implemented same-frame masks, the LR fraction and coupling-magnitude channels are exactly zero; Proposition 316 proves this from the role partition. The routine named compute_su2_gauge_link returns a scalar phase, whose representation properties are stated in Proposition 318. A fitted channel uses the actual operator, not the interpretation suggested by its name. Theorem 474 identifies the correlator keys that enter the mass fit.

For fixed correlator data, changing the time unit rescales every fitted rate and preserves rate ratios. Changing the time step or dynamics produces new data and need not preserve those ratios. Report the nonzero channels, fit windows, lag units, sampling uncertainty, and calibration inputs. Agreement then tests the declared correspondence at the measured resolution; continuum and physical-field identifications retain their own hypotheses.

How should I read the mathematical status of a claim?#

Follow the statement to its hypotheses and proof. The volume contains complete analytical chains: component drift and surviving-block bounds to finite-particle QSD convergence; normalized derivative calculus through actual greedy sampling to smooth fitness; structural LSI and full-generator dissipation to entropy convergence; and gain-loss well-posedness, contraction, and consistency to mean-field attraction and stationary chaos.

A later geometric or physical application uses the specific law, generator, representation, and scaling in that chain. Its remaining identifications are stated at the point where they enter. This distinguishes a proved mathematical implication from the task of verifying its inputs for a particular run.

Type of statement

What to check

Definition or construction

The specified data, domain, and operations

Proved implication

The complete argument under the stated hypotheses

Conditional application

The hypotheses that remain to be verified for the chosen algorithm

Conjecture

The precise proposed conclusion and the argument still missing

Numerical result

Implementation, estimator, uncertainty, and calibration

The latent analysis and continuum conditions make these distinctions explicit. Use the reference material and volume introduction to locate the surrounding arguments.