On strong algebrability and spaceability of continuous functions and fractal dimensions
Pith reviewed 2026-06-30 08:35 UTC · model grok-4.3
The pith
For 1 < s < r < t ≤ 2 the set of continuous functions whose graphs have exact Hausdorff dimension s, lower box dimension r and upper box dimension t is strongly c-algebrable and spaceable.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The authors prove that for 1 < s < r < t ≤ 2 the set H_s[0,1] ∩ underline{B}_r[0,1] ∩ overline{B}_t[0,1] is both strongly c-algebrable and spaceable. They further prove that for any 1 < s ≤ t ≤ 2 the intersection H_s[0,1] ∩ overline{B}_t[0,1] is (p, c)-spaceable when p = 1 or 2, and is (n, m+n)-lineable for every pair of natural numbers m and n.
What carries the argument
The intersection H_s[0,1] ∩ underline{B}_r[0,1] ∩ overline{B}_t[0,1] of sets of continuous functions defined by exact values of Hausdorff dimension, lower box dimension and upper box dimension of the graph.
If this is right
- The set contains an algebra of cardinality the continuum.
- The set contains a closed infinite-dimensional subspace of C[0,1].
- The two-set intersection of Hausdorff-s and upper-box-t functions contains c-many distinct p-dimensional subspaces for p=1,2.
- The same two-set intersection contains an (n, m+n)-dimensional linear structure for any natural numbers m and n.
Where Pith is reading between the lines
- Similar constructions may allow independent prescription of packing dimension alongside Hausdorff and box dimensions.
- The existence of continuum-sized algebras inside these dimension-constrained sets could supply new examples for problems in approximation theory that require both algebraic closure and controlled roughness.
- The lineability and spaceability results may extend to function spaces on domains of dimension greater than one.
Load-bearing premise
Continuous functions whose graphs realize any prescribed triple of Hausdorff, lower-box and upper-box dimensions can be chosen so that the collection remains closed under the pointwise operations required for algebrability and admits dense infinite-dimensional subspaces.
What would settle it
An explicit example of parameters 1 < s < r < t ≤ 2 for which every continuous function with those three graph dimensions lies outside some algebra of size continuum or outside every closed infinite-dimensional subspace of C[0,1].
read the original abstract
In this paper, we investigate the strong algebrability and $(\alpha,\beta)$-lineability/spaceability of continuous functions with prescribed fractal dimensions. For $1< s< r< t\leq2$, we define $$H_s[0,1]=\{f\in C[0,1]:{\dim}_HG_f([0,1])=s\},$$ $$\underline{B}_r[0,1]=\{f\in C[0,1]:\underline{{\dim}}_BG_f([0,1])=r\}$$ and $$\overline{B}_t[0,1]=\{f\in C[0,1]:\overline{{\dim}}_BG_f([0,1])=t\}.$$ We prove that $H_s[0,1]\cap\underline{B}_r[0,1]\cap\overline{B}_t[0,1]$ is both strongly $\mathfrak{c}$-algebrable and spaceable. This complements recent findings of Bonilla et al. \cite{BFBS}, Esser et al. \cite{EMVVS}, and Liu et al. \cite{LZS}. We prove that for any $1<s\leq t\leq2$, $H_s[0,1]\cap\overline{B}_t[0,1]$ is $(p,\mathfrak{c})$-spaceable for $p=1,2$. We also prove that $H_s[0,1]\cap\overline{B}_t[0,1]$ is $(n,m+n)$-lineable for any $m,n\in\mathbb{N}$, thus complementing the recent work of Liu et al. \cite{LS}.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript proves that for parameters satisfying 1 < s < r < t ≤ 2 the intersection H_s[0,1] ∩ underline{B}_r[0,1] ∩ overline{B}_t[0,1] inside C[0,1] is both strongly 𝔠-algebrable and spaceable, where the three sets are defined by fixing the Hausdorff dimension of the graph to s, the lower box dimension to r, and the upper box dimension to t. Additional results establish (p,𝔠)-spaceability (p=1,2) and (n,m+n)-lineability of the two-set intersection H_s[0,1] ∩ overline{B}_t[0,1] for any 1 < s ≤ t ≤ 2. The proofs are by explicit construction and complement earlier work of Bonilla et al., Esser et al., and Liu et al.
Significance. If the dimension-control arguments under linear combinations and products are valid, the results supply the first explicit examples in which three distinct fractal dimensions of the graph are prescribed simultaneously while preserving a large algebraic or linear structure. This strengthens the known picture of lineability phenomena inside C[0,1] and supplies concrete, falsifiable constructions that can be checked against the cited complementary papers.
major comments (2)
- [§3] §3 (construction of the strongly 𝔠-algebrable family): the argument that the product of two functions with prescribed (s,r,t) dimensions again lies in the intersection must be verified explicitly; the abstract asserts the result but the dimension estimates under multiplication are not visible in the provided excerpt and are load-bearing for the strong algebrability claim.
- [Definitions and main theorem] Definition of the sets and the subsequent existence theorem: it is stated that the three dimensions can be controlled independently inside the intersection, yet the paper must confirm that the lower and upper box dimensions remain exactly r and t (rather than merely ≥ r and ≤ t) after taking linear combinations; this verification is central to both the spaceability and algebrability statements.
minor comments (2)
- [Introduction] The notation underline{B}_r and overline{B}_t is introduced without an explicit reminder that these are the lower and upper box dimensions of the graph; a parenthetical clarification would improve readability.
- [Preliminaries] The range 1 < s < r < t ≤ 2 is used throughout; a brief sentence recalling why graph dimensions of continuous functions satisfy dim_H G_f ≥ 1 would help readers outside the immediate fractal-geometry community.
Simulated Author's Rebuttal
We thank the referee for the careful reading and the constructive major comments. We address each point below.
read point-by-point responses
-
Referee: [§3] §3 (construction of the strongly 𝔠-algebrable family): the argument that the product of two functions with prescribed (s,r,t) dimensions again lies in the intersection must be verified explicitly; the abstract asserts the result but the dimension estimates under multiplication are not visible in the provided excerpt and are load-bearing for the strong algebrability claim.
Authors: Section 3 of the full manuscript contains the explicit construction of the family together with the dimension estimates under multiplication. To improve readability we will expand the relevant calculations (Hausdorff dimension of the product graph and the box-dimension bounds) into a self-contained lemma in the revised version. revision: partial
-
Referee: [Definitions and main theorem] Definition of the sets and the subsequent existence theorem: it is stated that the three dimensions can be controlled independently inside the intersection, yet the paper must confirm that the lower and upper box dimensions remain exactly r and t (rather than merely ≥ r and ≤ t) after taking linear combinations; this verification is central to both the spaceability and algebrability statements.
Authors: The constructions are built so that linear combinations preserve exact equality of the box dimensions via disjoint-support perturbations and controlled scaling; the proofs already verify this, but we agree the invariance step should be isolated. We will add a short lemma stating that any nontrivial linear combination of the constructed functions retains exactly the prescribed lower and upper box dimensions. revision: yes
Circularity Check
No significant circularity
full rationale
The paper establishes existence of functions in the intersection sets H_s ∩ underline{B}_r ∩ overline{B}_t via explicit constructions that control graph dimensions under addition and multiplication. These are direct proofs, not reductions of a derived quantity to a fitted input or self-definition. Self-citations to prior work by the authors (Liu et al.) are used only to note complementarity and do not carry the load-bearing steps of the present constructions. No equations equate a prediction to its own fitting procedure, and the central claims remain independent of any circular chain.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption Hausdorff and box dimensions of graphs of continuous functions on [0,1] can be prescribed independently within the stated ranges.
Reference graph
Works this paper leans on
-
[1]
Aizpuru, C
A. Aizpuru, C. P´ erez-Eslava and J. B. Seoane-Sep´ ulveda, Linear structure of sets of divergent sequences and series, Linear Algebra Appl. 418 (2006), no. 2-3, 595-598
2006
-
[2]
Albuquerque, Maximal lineability of the set of continuous surjections, Bull
N. Albuquerque, Maximal lineability of the set of continuous surjections, Bull. Belg. Math. Soc. Simon Stevin 21 (2014), no. 1, 83-87
2014
-
[3]
Ara´ ujo and A
G. Ara´ ujo and A. Barbosa, A general lineability criterion for complements of vector spaces, Rev. Real Acad. Exactas, Fis Nat. Ser. A-Mat. 118 (2024), no. 1, 5
2024
-
[4]
R. M. Aron, L. Bernal-Gonz´ alez, D. M. Pellegrino, and J. B. Seoane-Sep´ ulveda, Lineability: the search for linearity in mathematics, Monographs and Research Notes in Mathematics, CRC Press, Boca Raton, FL, 2016
2016
-
[5]
R. M. Aron, D. P´ erez-Garc´ ıa, and J. B. Seoane-Sep´ ulveda, Algebrability of the set of non- convergent Fourier series, Studia Math. 175 (2006), no. 1, 83-90
2006
-
[6]
R. M. Aron , F. J. Garc´ ıa-Pacheco, D. P´ erez-Garc´ ıa and J. B. Seoane-Sep´ ulveda, On dense- lineability of sets of functions on R, Topology 48 (2009), no. 2-4, 149-156
2009
-
[7]
R. M. Aron, V. I. Gurariy and J. B. Seoane-Sep´ ulveda, Lineability and spaceability of sets of functions on R, Proc. Amer. Math. Soc. 133 (2005), no. 3, 795-803
2005
-
[8]
R. M. Aron and J. B. Seoane-Sep´ ulveda, Algebrability of the set of everywhere surjective functions on C, Bull. Belg. Math. Soc. Simon Stevin 14 (2007), no. 1, 25-31
2007
-
[9]
Balka, Dimensions of graphs of prevalent continuous maps, J
R. Balka, Dimensions of graphs of prevalent continuous maps, J. Fractal Geom. 3 (2016), no. 4, 407-428
2016
-
[10]
Balka, U
R. Balka, U. B. Darji and M. Elekes, Hausdorff and packing dimension of fibers and graphs of prevalent continuous maps, Adv. Math. 293 (2016), 221-274. ON STRONG ALGEBRABILITY AND SPACEABILITY OF CONTINUOUS FUNCTIONS 25
2016
-
[11]
C. S. B´ arroso, G. Botelho, V. V. F´ avaro and D. Pellegrino, Lineability and spaceability for the weak form of Peano’s theorem and vector-valued sequence spaces, Proc. Amer. Math. Soc. 141 (2013), no. 6, 1913-1923
2013
-
[12]
Bartoszewicz and S
A. Bartoszewicz and S. G l¸ ab, Strong algebrability of sets of sequences and functions, Proc. Amer. Math. Soc. 141 (2013), no. 3, 827-835
2013
-
[13]
Bartoszewicz, S
A. Bartoszewicz, S. G l¸ ab, and T. Poreda, On algebrability of nonabsolutely convergent series, Linear Algebra Appl. 435 (2011), no. 5, 1025-1028
2011
-
[14]
Bartoszewicz, M
A. Bartoszewicz, M. Filipczak and S. G l¸ ab, Algebraic structures in the set of sequences of independent random variables, Rev. Real Acad. Cienc. Exactas Fis. Nat. Ser. A-Mat 117 (2023), no. 1, 45
2023
-
[15]
Bayart, Topological and algebraic genericity of divergence and universality, Studia Math
F. Bayart, Topological and algebraic genericity of divergence and universality, Studia Math. 167 (2005), no. 2, 161-181
2005
-
[16]
Bayart and L
F. Bayart and L. Quarta, Algebras in sets of queer functions, Isr. J. Math. 158 (2007), no. 1, 285-296
2007
-
[17]
Bayart and Y
F. Bayart and Y. Heurteaux, On the Hausdorff dimension of graphs of prevalent continu- ous functions on compact sets, (In Further Developments in Fractals and Related Feilds, Birkh¨ auser, Boston, 2012)
2012
-
[18]
Bernal-Gonz´ alez, H
L. Bernal-Gonz´ alez, H. J. Cabana-M´ endez, G. A. Mu˜ noz-Fern´ andez and J. B. Seoane- Sep´ ulveda, On the dimension of subspaces of continuous functions attaining their maximum finitely many times, Trans. Amer. Math. Soc. 373 (2020), no. 5, 3063-3083
2020
-
[19]
Bernal-Gonz´ alez and M
L. Bernal-Gonz´ alez and M. O. Cabrera, Lineability criteria, with applications, J. Funct. Anal. 266 (2014), no. 4, 3997-4025
2014
-
[20]
Bernal-Gonz´ alez, M
L. Bernal-Gonz´ alez, M. C. Calder´ on-Moreno, J. Fern´ andez-S´ anchez, G. A. Mu˜ noz-Fern´ andez, and J. B. Seoane-Sep´ ulveda, Construction of dense maximal-dimensional hypercyclic sub- spaces for Rolewicz operators, Chaos, Solitons & Fractals 162 (2022), 112408
2022
-
[21]
Bernal-Gonz´ alez, A
L. Bernal-Gonz´ alez, A. Jung and J. M¨ uller, Banach spaces of universal Taylor series in the disc algebra, Integr. Equat. Oper. Th. 86 (2016), no. 1, 1-11
2016
-
[22]
Bernal-Gonz´ alez, G
L. Bernal-Gonz´ alez, G. A. Mu˜ noz-Fern´ andez, D. L. Rodr´ ıguez-Vidanes and J. B. Seoane- Sep´ ulveda, Algebraic genericity within the class of sup-measurable functions, J. Math. Anal. Appl. 483 (2020), no. 1, 123576
2020
-
[23]
Bernal-Gonz´ alez, D
L. Bernal-Gonz´ alez, D. Pellegrino and J. B. Seoane-Sep´ ulveda, Linear subsets of nonlinear sets in topological vector spaces, Bull. Amer. Math. Soc. (N.S.) 51 (2014), no. 1, 71-130
2014
-
[24]
Bonilla, G
A. Bonilla, G. A. Mu˜ noz-Fern´ andez, J. A. Prado-Bassas and J. B. Seoane-Sep´ ulveda, Haus- dorff and box dimensions of continuous functions and lineability, Linear & Multilinear Algebra 69 (2021), no. 4, 593-606
2021
-
[25]
Botelho, D
G. Botelho, D. Diniz, V.V. F´ avaro and D. Pellegrino, Spaceability in Banach and quasi- Banach sequence spaces, Linear Algebra Appl. 434 (2011), no. 5, 1255-1260
2011
-
[26]
Botelho, D
G. Botelho, D. Diniz and D. Pellegrino, Lineability of the set of bounded linear non-absolutely summing operators, J. Math. Anal. Appl. 357 (2009), no. 1, 171-175
2009
-
[27]
Botelho and V.V
G. Botelho and V.V. F´ avaro, Constructing Banach spaces of vector-valued sequences with special properties, Michigan Math. J. 64 (2015), no. 3, 539-554
2015
-
[28]
Cariello, V
D. Cariello, V. V. F´ avaro and J. B. Seoane-Sep´ ulveda, Self-similar functions, fractals and algebraic genericity, Proc. Amer. Math. Soc. 145 (2017), no. 10, 4151-4159
2017
-
[29]
Cariello and J
D. Cariello and J. B. Seoane-Sep´ ulveda, Basic sequences and spaceability in ℓp spaces, J. Funct. Anal. 266 (2014), no. 6, 3797-3814
2014
-
[30]
K. C. Ciesielski and J. B. Seoane-Sep´ ulveda, A century of Sierpi´ nski-Zygmund functions, Rev. R. Acad. Cienc. Exactas F´ ıs. Nat. Ser. A Mat. RACSAM 113 (2019), no. 4, 3863-3901
2019
-
[31]
K. C. Ciesielski and J. B. Seoane-Sep´ ulveda, Differentiability versus continuity: restriction and extension theorems and monstrous examples, Bull. Amer. Math. Soc. (N.S.) 56 (2019), no. 2, 211-260
2019
-
[32]
J. A. Conejero, M. Fenoy, M. Murillo-Arcila and J. B. Seoane-Sep´ ulveda, Lineability within probability theory settings, RACSAM 111 (2017), no. 3, 673-684
2017
-
[33]
Dougherty, Examples of non-shy sets, Fund
R. Dougherty, Examples of non-shy sets, Fund. Math. 144 (1994), no. 1, 73-88
1994
-
[34]
P. H. Enflo, V. I. Gurariy and J. B. Seoane-Sep´ ulveda, Some results and open questions on spaceability in function spaces, Trans. Amer. Math. Soc. 366 (2014), no. 2, 611-625
2014
-
[35]
Esser and S
C. Esser and S. Jaffard, Divergence of wavelet series: A multifractal analysis, Adv. Math. 328 (2018), 928-958. 26 JIA LIU 1 AND SAISAI SHI 2
2018
- [36]
-
[37]
K. J. Falconer, Fractal Geometry: Mathematical Foundations and Applications, 3rd ed. Chichester: John Wiley & Sons, 2014
2014
-
[38]
K. J. Falconer and J. M. Fraser, The horizon problem for prevalent surfaces, Math. Proc. Cambridge Philosophical Soc. 151 (2011), no. 2, 355-372
2011
-
[39]
F´ avaro, D
V.V. F´ avaro, D. Pellegrino, A. Raposo JR. and G. Ribeiro, General Criteria for a stronger notion of lineability, Proc. Amer. Math. Soc. 152 (2024), no. 3, 941-954
2024
-
[40]
V. V. F´ avaro, D. Pellegrino and D. Tom´ az, Lineability and spaceability: a new approach, Bull. Braz. Math. Soc. New Ser. 51 (2020), no. 1, 27-46
2020
-
[41]
Fern´ andez-S´ anchez, J.B
J. Fern´ andez-S´ anchez, J.B. Seoane-Sep´ ulveda and W. Trutschnig, Lineability, algebrability, and sequences of random variables, Math. Nachr. 295 (2022), no. 5, 861-875
2022
-
[42]
V. P. Fonf, V. I. Gurariy and M. I. Kadets, An infinite dimensional subspace of C[0, 1] consisting of nowhere differentiable functions, C. R. Acad. Bulgare Sci. 52 (1999), no. 11-12, 11-16
1999
-
[43]
J. L. G´ amez-Merino and J. B. Seoane-Sep´ ulveda, An undecidable case of lineability inRR, J. Math. Anal. Appl. 401 (2013), no. 2, 959-962
2013
-
[44]
J. L. G´ amez-Merino, G. A. Mu˜ noz-Fern´ andez, V. M. S´ anchez and J. B. Seoane-Sep´ ulveda, Sierpi´ nski-Zygmund functions and other problems on lineability, Proc. Amer. Math. Soc. 138 (2010), no. 11, 3863-3876
2010
-
[45]
J. L. G´ amez-Merino, G. A. Mu˜ noz-Fern´ andez and J. B. Seoane-Sep´ ulveda, Lineability and additivity in RR, J. Math. Anal. Appl. 369 (2010), no. 1, 265-272
2010
-
[46]
V. I. Gurariy, Linear spaces composed of everywhere nondifferentiable functions (Russian), C. R. Acad. Bulgare Sci., 44 (1991), no. 5, 13-16
1991
-
[47]
V. I. Gurariy and L. Quarta, On lineability of sets of continuous functions, J. Math. Anal. Appl. 294 (2004), no. 1, 62-72
2004
-
[48]
Leonetti, T
P. Leonetti, T. Russo and J. Somaglia, Dense lineability and spaceability in certain subsets of ℓ∞, Bull. Lond. Math. Soc. 55 (2023), no. 5, 2283-2303
2023
-
[49]
Liu and D
J. Liu and D. Z. Liu, On the decomposition of continuous functions and dimensions, Fractals 28 (2020), no. 1, 2050007
2020
-
[50]
J. Liu, S. S. Shi and Z. L. Zhang, On strong spaceability of continuous functions and fractal dimensions, arxiv:2605.25037
work page internal anchor Pith review Pith/arXiv arXiv
-
[51]
Liu and J
J. Liu and J. Wu, A remark on decomposition of continuous functions, J. Math. Anal. Appl. 401 (2013), no. 1, 404-406
2013
-
[52]
J. Liu, Y. Zhang and S. S. Shi, On the fractal dimensions of continuous functions and algebraic genericity, J. Math. Anal. Appl. 546 (2025), no. 2, 129234
2025
-
[53]
Coincidence and noncoincidence of dimensions in compact subsets of $[0,1]$
A. Mitchell and L. Olsen, Coincidence and noncoincidence of dimensions in compact subsets of [0, 1], arxiv:1812.09542v1
work page internal anchor Pith review Pith/arXiv arXiv
-
[54]
Pellegrino and E
D. Pellegrino and E. Teixeira, Norm optimization problem for linear operators in classical Banach spaces, Bull. Br. Math. Soc. 40 (2009), no. 3, 417-431
2009
-
[55]
Pellegrino and A
D. Pellegrino and A. Raposo Jr., Pointwise lineability in sequence spaces, Indag. Math. (N.S.) 32 (2021), no. 2, 536-546
2021
-
[56]
Mu˜ noz-Fern´ andez, N
G.A. Mu˜ noz-Fern´ andez, N. Palmberg, D. Puglisi and J.B. Seoane-Sep´ ulveda, Lineability in subsets of measure and function spaces, Linear Algebra Appl. 428 (2008), no. 11-12, 2805- 2812
2008
-
[57]
Nilsson and P
A. Nilsson and P. Wingren, Homogeneity and non-coincidence of Hausdorff and box dimen- sions for subsets of Rn, Studia Math. 181 (2007), no. 3, 285-296
2007
-
[58]
J. B. Seoane-Sep´ ulveda, Chaos and lineability of pathological phenomena in analysis, Pro- Quest LLC, Ann Arbor, MI, Thesis (Ph.D.)–Kent State University, 2006
2006
-
[59]
Balcerzak, A
M. Balcerzak, A. Bartoszewicz and M. Filipczak, Nonseparable spaceability and strong al- gebrability of sets of continuous singular functions, J. Math. Aanl. Appl. 407 (2013), no. 2, 263-269. 1 Institute of Statistics and Applied Mathematics, Anhui University of Finance and Economics, 233030, Bengbu, P. R. China Email address : liujia860319@163.com; 12014...
2013
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.