Weighted Total Persistence in TDA
- Weighted Total Persistence is a family of aggregate functionals that weight persistence diagram intervals by their lifetimes or endpoint-dependent kernels to capture geometric features.
- Its degree-p formulation and analytic bounds convert geometric properties into quantitative persistence moments, ensuring stability and robust control in TDA.
- The concept bridges applications from minimal spanning acycles to persistence-weighted kernels, enabling both theoretical insights and practical algorithmic implementations.
Searching arXiv for the cited papers to ground the article in current metadata. arXiv search query: (Skraba et al., 2017) Randomly Weighted d-complexes Minimal Spanning Acycles and Persistence Diagrams Weighted total persistence is a family of aggregate functionals on persistence diagrams that summarize barcode geometry by weighting intervals through their lifetimes or endpoint-dependent kernels. In the degree- form, it is the sum of persistence lengths with ; in randomly weighted -complexes with births in at $0$, it becomes and, for , the lifetime sum ; in persistent magnitude, it is replaced by the signed exponential weighting ; and in weighted persistence diagrams on metric measure spaces, it is the interval-moment functional 0 (Kusano et al., 2016, Skraba et al., 2017, Govc et al., 2019, Gülen et al., 16 Apr 2025). These formulations suggest that weighted total persistence is not a single invariant but a class of persistence summaries whose weights may be polynomial, bounded monotone, exponential, or measure-theoretic.
1. Definitions and principal formulations
A persistence diagram 1 is a multiset of points 2 with 3, together with the diagonal 4 counted with infinite multiplicity. The persistence of a point 5 is 6 (Kusano et al., 2016).
| Formulation | Formula | Source |
|---|---|---|
| Degree-7 total persistence | 8 | (Kusano et al., 2016) |
| Thresholded total persistence | 9 | (Kusano et al., 2016) |
| Birth-zero lifetime moments | 0 | (Skraba et al., 2017) |
| General barcode moment | 1 | (Skraba et al., 2017) |
| Persistent magnitude | 2 | (Govc et al., 2019) |
| Weighted-diagram moment | 3 | (Gülen et al., 16 Apr 2025) |
The literature represented by these papers does not impose a single universal definition. One paper explicitly defines degree-4 total persistence, one identifies weighted total persistence with sums of powers of death times when births are zero, one introduces a signed endpoint-weighted variant through persistent magnitude, and one places the construction on weighted diagrams endowed with a probability measure on intervals (Kusano et al., 2016, Skraba et al., 2017, Govc et al., 2019, Gülen et al., 16 Apr 2025). A plausible implication is that “weighted total persistence” is best understood as a design pattern for persistence summaries rather than as a uniquely standardized term.
2. Degree-5 total persistence and analytic bounds
In the sublevel-set formulation of persistent homology, for a tame Lipschitz function 6 on a triangulable compact metric space, the thresholded degree-7 total persistence is
8
for 9, where 0. The full degree-1 total persistence is 2 (Kusano et al., 2016).
The analytic importance of this definition is that it admits explicit upper bounds in standard TDA settings. If 3 is triangulable and compact, 4 is tame and Lipschitz with Lipschitz constant 5, and 6 is the minimum number of simplices needed in a triangulation with mesh at most 7, then
8
When 9 and 0, the estimate 1 yields
2
For a finite subset 3, the function 4 satisfies 5 and 6, so
7
These inequalities are central because they convert geometric control of the underlying space into quantitative control of persistence moments (Kusano et al., 2016).
The same paper also proves monotonicity in the persistence exponent: if 8 and 9 is bounded, then $0$0 is also bounded. Equivalently, if $0$1, then $0$2, hence
$0$3
This places weighted total persistence in the same hierarchy of $0$4-type summaries that underlies many stability and approximation arguments (Kusano et al., 2016).
3. Minimal spanning acycles, death times, and lifetime sums
For a finite simplicial complex $0$5, a weighted $0$6-complex is a pair $0$7 in which $0$8 is monotone in the sense that $0$9 whenever 0. The associated filtration is the sublevel filtration 1. Within this framework, a subset 2 is spanning if 3, an acycle if 4, and a spanning acycle if both hold. The minimal spanning acycle 5 minimizes 6 among spanning acycles (Skraba et al., 2017).
The central structural result is the equivalence between minimal spanning acycle weights and persistence death times. If 7, 8 is the multiset of death times in 9, 0 is the multiset of birth times in 1, and 2 is a 3-minimal spanning acycle, then
4
This identification is obtained by comparing the Incremental Persistence Algorithm with the simplicial Kruskal algorithm: a 5-face is added to the MSA exactly when it is negative, and negative faces are exactly the faces whose weights are recorded as death times in 6 (Skraba et al., 2017).
A further identity, attributed there as the Hiraoka–Shirai identity, links lifetime sums to spanning acycle weights:
7
In the mean-field random model in which all lower-dimensional faces have weight 8, births in 9 occur at 0 and 1. Consequently,
2
and, more generally,
3
In this regime, weighted total persistence in degree 4 is literally the total weight, or the moment sequence of weights, of the 5-dimensional minimal spanning acycle (Skraba et al., 2017).
4. Stability and random asymptotics in weighted 6-complexes
The stability theorem for weighted 7-complexes compares two monotone weight functions 8 and 9 on the same finite complex. If 0 and 1 are the birth and death times under 2, and 3 and 4 are the corresponding sets under 5, then for any 6,
7
with the 8 case interpreted as a supremum. Via the equivalence between MSA weights and death times, the same bound applies to the multiset of MSA 9-face weights (Skraba et al., 2017).
In the mean-field model, where 00 for 01 and 02 on 03, this stability estimate yields continuity of total persistence moments under perturbations of the 04-face weights. The paper derives
05
and an accompanying expectation bound. For 06, the inequality simplifies to
07
so 08 is 09-Lipschitz with respect to the 10 change in 11-face weights up to optimal matching of death sets (Skraba et al., 2017).
The random model also supports a detailed extremal theory. If 12 is Lipschitz continuous and 13 in probability, then the scaled point processes of extremal nearest-face distances, extremal death times in 14, and extremal weights in the 15-MSA all converge vaguely in distribution to a Poisson point process on 16 with intensity 17. In particular,
18
This completely characterizes the extremal points of persistence diagrams and MSAs in the model (Skraba et al., 2017).
The same stability mechanism transfers classical random spanning-tree asymptotics to noisy higher-dimensional settings. If 19 is uniform on 20 and
21
then
22
For 23 and 24, this recovers Frieze’s 25 limit for random minimal spanning trees under suitable noise; for higher 26, it gives the corresponding asymptotics for random minimal spanning acycles and therefore for weighted total persistence in 27 (Skraba et al., 2017).
5. Persistence-weighted kernels and bounded monotone weighting
In the kernel approach of the persistence weighted Gaussian kernel, weighted total persistence appears both as a direct summary and as a control quantity for diagram embeddings. The weight assigned to a point 28 is
29
which is increasing in persistence. Near-diagonal points with small persistence receive small weight, while large-persistence points receive larger weight, and the saturation of 30 prevents unbounded influence (Kusano et al., 2016).
The weighted atomic measure associated with a diagram is
31
and the Gaussian RKHS embedding is
32
This yields the linear kernel
33
the RKHS distance 34, and the nonlinear Gaussian kernel on the RKHS
35
The analytic role of total persistence is explicit in the stability estimate
36
with
37
Thus the continuity of the weighted embedding is governed by degree-38 and degree-39 total persistence (Kusano et al., 2016).
For finite point clouds 40, the data-level theorem states that if 41, then
42
where the constant is independent of 43 and 44. The reason for the condition 45 is that uniform control of 46 and 47 over diagrams arising from finite subsets in 48 requires 49 (Kusano et al., 2016).
The method also has an explicit computational approximation via random Fourier features. Exact Gram-matrix computation among 50 diagrams of size at most 51 costs 52 kernel evaluations, while the random-feature approximation reduces this to 53 for 54 sampled frequencies. The same paper reports that, in a synthesized XOR-like classification problem, PWGK with the RKHS Gaussian kernel achieved approximately 55 test accuracy, compared to approximately 56 for PSSK and approximately 57 for an unweighted Gaussian embedding; in oxide-glass change-point detection it identified a change point converging to 58; and in two protein classification tasks it achieved 59 and 60 cross-validation accuracies (Kusano et al., 2016).
6. Persistent magnitude as signed exponential-weighted total persistence
Persistent magnitude defines a different weighting paradigm for barcodes. For a finitely presented graded persistence module 61 with half-open bars 62 appearing in degrees 63, the persistent magnitude is
64
with the convention 65. Because
66
each bar contributes an exponentially weighted length, and the sign 67 inserts Euler-characteristic cancellation across homological degrees (Govc et al., 2019).
The magnitude function introduces a scaling parameter:
68
This admits two equivalent interpretations. First, in terms of the associated graded functor,
69
Second, in terms of the Laplace transform, if 70 is the Euler characteristic curve, then
71
A discrete breakpoint formula is
72
where 73 list the distinct barcode endpoints (Govc et al., 2019).
These formulations imply strong formal properties. Persistent magnitude is additive with respect to short exact sequences:
74
It is also compatible with tensor products:
75
In settings with a Künneth short exact sequence for a graded persistent homology theory, this yields multiplicativity of magnitude under products (Govc et al., 2019).
Relative to standard total persistence,
76
persistent magnitude is a weighted total persistence with kernel 77 and with graded signs. It therefore differs from the unsigned polynomial moment 78 in two essential ways: it depends on endpoints through 79 rather than only on bar length, and it is alternating across homological degree. The paper further shows that the magnitude of a finite metric space is precisely the persistent magnitude of its blurred magnitude homology, providing a bridge between classical magnitude and persistent homology (Govc et al., 2019).
7. Weighted persistence diagrams on metric measure spaces
A more recent framework defines weighted persistence diagrams functorially from finite metric measure spaces 80, where 81 is a fully supported probability measure. The weighted Vietoris–Rips filtration is built from the finite index set
82
together with the global distribution of distances
83
The filtration is
84
From a weighted filtration 85, the weighted persistence diagram is
86
with 87 (Gülen et al., 16 Apr 2025).
In this setting, weighted total persistence is defined by
88
where 89. If multiplicities are also incorporated, the alternative definition is
90
For weighted Vietoris–Rips diagrams, the moment has the explicit probabilistic interpretation
91
because flipping does not change 92. Hence weighted total persistence captures the 93-th absolute moment of pairwise distance differences drawn from the global distance distribution (Gülen et al., 16 Apr 2025).
Differences between weighted diagrams are measured by a 94-edit distance with an optimal-transport-like reformulation. The main stability theorem states that for all 95,
96
From this, one obtains a robustness bound for weighted total persistence:
97
and therefore
98
where 99 bounds the index range (Gülen et al., 16 Apr 2025).
This framework also sharpens the distinction between topology and weighting. The paper shows that two 00-point ultrametric spaces can have identical Vietoris–Rips persistence diagrams in all degrees yet different weighted diagrams because their 01 differ. It also proves that for 02, the weighted edit distance is most discriminative, while for finite 03 it may become insensitive to diagram multiplicities and depend primarily on the weight distribution, although interval ordering can still distinguish cases where the flipped-GDD Gromov–Wasserstein distance is zero (Gülen et al., 16 Apr 2025). A concrete toy calculation illustrates the moment interpretation: if 04 is uniform on 05, then
06
These are exactly the weighted total persistence values of the associated weighted Vietoris–Rips diagram (Gülen et al., 16 Apr 2025).
Taken together, these developments place weighted total persistence at the intersection of persistent homology, random topology, kernel methods, categorical invariants, and metric-measure stability theory. The common theme is aggregation of barcode information under a prescribed weighting rule, but the rule itself varies substantially across settings: polynomial lifetime moments, bounded persistence weights, exponential endpoint kernels, and probability measures on intervals each produce distinct invariants with distinct formal and statistical properties (Kusano et al., 2016, Skraba et al., 2017, Govc et al., 2019, Gülen et al., 16 Apr 2025).