REVIEW 4 major objections 6 minor 47 references
Positive solutions of inhomogeneous Kirchhoff type equations with indefinite data
T0 review · 4 major / 6 minor · reviewed 2026-08-14 · deepseek-v4-flash
Pith's one-line read For large b and subcritical exponents, positive Kirchhoff solvability is equivalent to the linear problem being solvable.
desk verdict A credible, mostly correct extension of the semilinear theory to Kirchhoff equations; the main iff theorem leans on an imported lemma that the paper should either prove or quote precisely. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
b_0$, positive solvability for every $\lambda>0$ is exactly equivalent to $f$ lying in the set $M$ of data for which the linear problem $-\Delta v=f$, $v\ge 0$, $v|_{\partial\Omega}=0$ is solvable. In that regime the solution is also unique for small $\lambda$ when $\alpha\ge 1/2$. A sympathetic reader should care because it shows the nonlocal term does not obstruct solvability: the whole Kirchhoff problem inherits its solvability profile from a linear Poisson problem, in contrast to the semilinear case where a finite $\lambda$ threshold and two solutions appear. The paper also establishes multiplicity in the intermediate range $2\alpha+1
2^*$ on starshaped domains.
What carries the argument
The central objects are the data set $M$, the threshold $b_0=(p-1)\gamma^{\gamma/(p-1)}(2\alpha l)^{-2\alpha/(p-1)}$ with $\gamma=2\alpha+1-p$ and $l=S^{(p+1)/2}(\Omega)$, and the scaling identity connecting Kirchhoff solutions to linear ones. If $u$ solves (1.1), then $v=(1+b\|\nabla u\|_2^{2\alpha})u/\lambda$ solves $-\Delta v=f$, and conversely a solution of the linear problem yields a Kirchhoff solution once an algebraic equation in the nonlocal coefficient is solved. The threshold $b_0$ enters through Lemma 2.4, which rules out positive solutions of the homogeneous problem $-(1+b\|\nabla u\|_2^{2\alpha})\Delta u=u^p$, making the small-$\lambda$ limit vanish and thereby driving the necessity of $f\in M$. In the supercritical range, the Pohozaev identity and an iterative comparison sequence replace the variational machinery.
What would settle it
Find a positive classical solution of the homogeneous Kirchhoff problem $-(1+b\|\nabla u\|_2^{2\alpha})\Delta u=u^p$, $u>0$, $u|_{\partial\Omega}=0$, on a bounded smooth domain with $1<p<2\alpha+1$ and $b>b_0$; any such solution contradicts Lemma 2.4 and therefore the necessity in Theorem 2.2. Alternatively, for an $f$ known not to lie in $M$, any positive solution of (1.1) for large $\lambda$ would refute the theorem's nonexistence conclusions.
Extended reading notes
Core claim
The main discovery, Theorem 2.2, is that for $1<p<2\alpha+1$ and $b>b_0$, the problem (1.1) has a positive solution for every $\lambda>0$ if and only if $f\in M$, and for $\alpha\ge 1/2$ the positive solution is unique when $\lambda$ is small. The necessity proof sets $u_\lambda=\lambda v_\lambda$, shows that $v_\lambda$ stays bounded through elliptic estimates, and lets $\lambda\to0$; the imported no-solution lemma for the homogeneous Kirchhoff problem forces $u_\lambda\to0$, so the limit $v$ is a nonnegative solution of the linear problem $-\Delta v=f$. The sufficiency direction starts from a solution $v$ of the linear problem and rescales it by the nonlocal coefficient, while the variational argument with Ekeland's principle produces the positive solution. In the supercritical case $p>2^*$ on starshaped domains, Theorem 4.1 proves the analogous equivalence for small $\lambda$, with the Pohozaev identity supplying the uniform bound that makes the limiting linear solution nontrivial.
Load-bearing premise
The argument's 'only if' direction relies on an imported lemma that the homogeneous Kirchhoff problem has no positive solution when $b>b_0$ and $1<p<2\alpha+1$; if that lemma is false, the equivalence collapses.
Editorial extensions
If this is right
- For $1<p<2\alpha+1$, membership in $M$ alone guarantees a positive solution for every $\lambda>0$, with no restriction on $b$.
- For $b>b_0$, the converse holds: if a positive solution exists for every $\lambda>0$, then $f\in M$, so $M$ is the exact data class in this regime.
- For small $\lambda$ and $\alpha\ge 1/2$, the positive solution is unique when $b>b_0$; the nonlocal effect suppresses the second solution seen in the semilinear case.
- For $2\alpha+1<p<2^*$, data in $M$ produce at least two positive solutions for small $\lambda$ and no solution for large $\lambda$.
- For $p>2^*$ on starshaped domains, small-$\lambda$ existence is equivalent to $f\in M$ and no positive solution exists for large $\lambda$.
Reading between the lines
- One could test the sharpness of $b_0$ numerically: if the homogeneous Kirchhoff problem develops a positive solution exactly at $b=b_0$, then the threshold in (1.5) is optimal rather than merely sufficient.
- The convergence $u_\lambda/\lambda\to v$ in the necessity proof suggests that, for $b>b_0$, the unique small-$\lambda$ solution is asymptotic to $\lambda$ times the minimal linear solution; this asymptotic could be used to recover membership in $M$ from solution data.
- The same scaling identity should extend to more general nonlocal coefficients $M(\|\nabla u\|_2)$ as long as the associated algebraic equation is monotone and a no-solution lemma holds; the failure of the comparison principle is the main obstacle.
Signed reviews
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper studies positive solutions of the inhomogeneous Kirchhoff-type Dirichlet problem (1.1) with sign-changing data f. It introduces the set M of data for which the linear problem -Δu=f, u≥0 is solvable, and establishes: (i) for 1<p<2α+1 and f∈M, a positive solution exists for every λ>0; (ii) if, in addition, b>b0 for the constant in (1.5), positive solvability for every λ>0 is equivalent to f∈M, with uniqueness for small λ when α≥1/2; (iii) for 2α+1<p<2* and f∈M, two positive solutions exist for small λ and none for large λ; (iv) for p>2* on starshaped domains, existence for small λ is equivalent to f∈M, with nonexistence for large λ. The proofs combine variational methods, comparison principles, algebraic constructions, and several imported a priori results. The central claims are plausible, but the manuscript as written has important gaps in the imported lemmas and in the iterative scheme of Section 4.
Significance. If correct, the paper gives a fairly complete description of how the nonlocal coefficient changes the solvability profile relative to the semilinear problem: in the range 1<p<2α+1 and for large b, the λ-restriction disappears and the solution is unique for small λ. The variational arguments in Sections 2 and 3 are mostly standard and the strong-convergence and positivity steps are handled carefully. The proposed iteration for the supercritical case in Section 4 is a useful idea even though the well-definedness step needs repair. The paper is a potentially valuable contribution to the Kirchhoff-type literature, but the heavy reliance on unproved external lemmas, especially Lemma 2.4, means the central equivalence theorem is not self-contained in its present form.
major comments (4)
- [Section 2, Lemma 2.4] The 'only if' direction of Theorem 2.2 rests on Lemma 2.4, the assertion that for 1<p<2α+1 and b>b0 the homogeneous problem (2.15) has no positive solution. This lemma is quoted from [17] without proof and without a statement of the hypotheses under which it is established. In Lemma 2.5, the convergence of uλ to 0 is proved by contradiction, and the contradiction uses exactly this no-solution result; if [17] proves a different statement (for example, with a different normalization of b0 or under additional domain/geometry assumptions), the passage (2.24)-(2.30) does not yield f∈M. Please either reproduce a self-contained proof of Lemma 2.4 or state the result from [17] with full hypotheses and verify that all of them are satisfied in the present setting. The scaling argument (mapping a solution u of (2.15) to v=u/(1+b||∇u||^{2α})^{1/(p-1)}, which solves -Δv=v^p, and comparing the algebraic relation c^{p-1}=1+b c^{2α}||∇v||^2 with the Sobolev lower bound) shows the lemma is plausible, so this is a missing-support concern rather than a counterexample.
- [Section 4, Eq. (4.5)] The iteration in Lemma 4.2 defines u_{n+1} by the problem -(1+b||∇u_{n+1}||^{2α})Δu_{n+1}=u_n^p+λf. This is not a linear Dirichlet problem for u_{n+1}, because the coefficient depends on the unknown function u_{n+1} itself. The manuscript proceeds as though existence of u_{n+1} were immediate, and the subsequent comparison estimates (4.9)-(4.12) and the Schauder bound all rely on that step. The gap is repairable: since u_n^p+λf∈M when f∈M and u_n is a bounded nonnegative function, one may apply Lemma 2.3 to obtain u_{n+1}. Please add this justification, or an equivalent fixed-point argument, before the induction.
- [Section 3, Lemma 3.5] The nonexistence parts of Theorems 3.1 and 4.1 rely on Lemma 3.6, which imports Lemma 3.5 from [16,19] as a black box, including the uniform bound ||∇uλ||2≤C for all solutions of the semilinear problem (3.21) for λ∈(0,λf). This uniform bound is essential for inequality (3.24) and for the definition of Λf at the end of Lemma 3.6. Please state Lemma 3.5 as a precise theorem with all hypotheses, and either indicate where each assertion is proved in [16,19] or provide a proof sketch, so that the reader can verify that the uniformity in λ holds for all f∈M and for all solutions, not only for the constructed solutions.
- [Section 2, Lemma 2.6] In the uniqueness proof, the assertion that C2(λ)+||∇vλ||2C1(λ)→0 as λ→0 uses Lemma 2.5, which gives only L∞ decay of uλ and vλ. However, C1(λ) contains the H01 norms ||∇uλ||2 and ||∇vλ||2, so the stated convergence requires also that these H01 norms tend to zero. That fact does follow by multiplying (2.16) by uλ and integrating, but the argument is not given. Please include this step, since it is needed for the uniqueness claim in Theorem 2.2.
minor comments (6)
- [Title and abstract] There are typographical errors in the title ('Positve') and in the abstract formatting; these should be corrected.
- [Section 2, Lemma 2.3] The equation for h(y) is typeset incorrectly: it should read h(y)=b y^{α+1/2}+y^{1/2}-λ||∇v||_2, with a subscript on the norm.
- [Section 2, before (2.13)] There is an extra parenthesis in the displayed equation for ϕ: '−(1 +b‖∇ϕ‖2α )2 )∆ ϕ' should be '−(1 +b‖∇ϕ‖2α)∆ ϕ'.
- [Section 3, Lemma 3.3, Step 1] The definition of βf appears dimensionally inconsistent: the estimate (3.9) requires λ^2/λ1(Ω)||f||_2^2≤E1/4, which imposes βf of order sqrt(λ1(Ω)E1)/||f||_2. Please clarify the formula and the choices of βf and E0.
- [Section 3, Lemma 3.4] The choice of λ* after the estimate ||∇ϕλ||2≤ρ0/√2 appears to have a missing factor; the displayed formula should be checked so that the intended bound is transparent.
- [Section 4, inequalities (4.10) and (4.12)] The comparison argument can be made more transparent by writing, for instance, -Δ(u_{k+1}-φλ/(1+b||∇u_{k+1}||^{2α}))≥0 with zero boundary values, so that the positivity of the factor in the denominator is explicit; the current wording is slightly compressed.
Circularity Check
No significant circularity: the main existence and necessity arguments are variational, compactness, and scaling based; the only self-citation burden is the black-box import of Lemma 2.4 from the authors' earlier paper.
full rationale
The sufficiency direction (Theorem 2.1) is self-contained: Iλ is coercive for 1 < p < 2α + 1, Ekeland's principle yields a critical point, and comparison with the auxiliary solution of (2.1) supplied by Lemma 2.3 gives positivity. Lemma 2.3 itself is proved in the paper by an algebraic fixed-point reduction to the linear problem defining M, so it is not circular. The necessity direction of Theorem 2.2 uses Lemma 2.5, whose contradiction argument would produce a nontrivial nonnegative solution of the homogeneous Kirchhoff problem if ‖uλ‖∞ did not tend to 0; Lemma 2.4, quoted from [17], rules that out. This is an external published theorem, not a restatement of the target result, and the paper does not fit any parameter to make it true. The same holds for Lemma 3.5 from [16,19], used in Lemma 3.6 through the explicit scaling v = u/(1+b‖∇u‖^{2α})^{1/(p-1)}; this is a reduction to a different semilinear problem, not a renaming of the Kirchhoff conclusion. The only genuinely load-bearing self-citation is Lemma 2.4, imported without proof or stated auxiliary hypotheses, so the necessity direction is not auditable from the manuscript alone. That is a missing-support and correctness-risk issue, not a definitional or constructional circularity, and I therefore assign a low score of 2 to reflect the black-box self-citation while emphasizing that no step identifies a prediction with a fitted input or derives the theorem from its own conclusion.
Assumptions & free parameters
assumptions (5)
- standard math Sobolev embedding, Poincare, Holder and Young inequalities; Ekeland variational principle; mountain pass theorem; strong maximum principle; Schauder and elliptic regularity.
- domain assumption Omega is a bounded domain in R^N with smooth boundary; f is in C^1(Omega bar) \ {0}; b > 0, p > 1, alpha in the stated range.
- domain assumption Lemma 2.4 of [17]: for 1 < p < 2 alpha + 1 and b > b0, the homogeneous problem (2.15) has no positive solution.
- domain assumption Lemma 3.5 of [16,19]: semilinear problem (3.21) has a solution for lambda in (0, lambda_f) and none for lambda > lambda_f, with a uniform gradient bound.
- standard math Pohozaev identity of [25] for classical solutions of Delta omega + g(x, omega) = 0.
Cite this review
Pith. "Pith review of Positive solutions of inhomogeneous Kirchhoff type equations with indefinite data." pith.science (2026). https://pith.science/paper/UF367ME5
@misc{pith2026190806562,
author = {Pith},
title = {Pith review of: Positive solutions of inhomogeneous Kirchhoff type equations with indefinite data},
year = {2026},
howpublished = {\url{https://pith.science/paper/UF367ME5}},
note = {Machine review of arXiv:1908.06562}
}
read the original abstract
Inhomogeneous Kirchhoff type equations with indefinite data are considered. Some necessary and sufficient conditions for the existence of positive solutions of the problem under consideration are presented.
Reference graph
Works this paper leans on
-
[17]
Q. Y. Dai, E. H. Lan, F. L. Shi, A priori bounds for positiv e solutions of Kirchhoff type equations, Comput. Math. Appl., 76 (6)(2018),1525-15 34
work page 2018
-
[1]
G. A. Afrouzi, N. T. Chung, S. Shakeri, Exstence of positi ve solutions for Kirchhoff type equations, Electron.J.Differential Equations, 2013(1 80)(2013), 1-8
work page 2013
-
[2]
C. O. Alves, F. J. S. A. Correa, On existence of solutions f or a class of problem involving a nonlinear operator, Comm. Appl. Nonlinear Anal ., 8(2001), 43-56
work page 2001
-
[3]
D. Andrade, T. F. Ma, An operator equation suggested by a c lass of stationary problems, Comm. Appl. Nonlinear. Anal., 4 (1997), 65-71
work page 1997
- [4]
-
[5]
Azorero J G,Alonso I P,Some results about the existence o f a second positive solution in quasilinear critical problem,Indiana Univers ity Mathematics Journal. 43 (1994) 941-957
work page 1994
-
[6]
A. Azzollini, The elliptic Kirchhoff equation in RN perturbed by a local nonlin- earity, Differential Integral Equations, 25 (2012), 543-554
work page 2012
- [7]
Show all 47 references
-
[8]
Bahri, H
A. Bahri, H. Berestycki, A perturbation method in critic al point theory and ap- plications, Trans. Amer. Math. Soc., 267 (1981), 1-32
1981
-
[9]
Bahri, P
A. Bahri, P. L. Lions, Morse index of some min-max critica l points I-application to multiplicity results, Comm. Pure Appl. Math., XLI. (1988 ), 1027-1037
1988
-
[10]
M. M. Cavalcante, V. N. D. Cavalcante, J. A. Soriano, Glo bal existence and uniform decay rates for the Kirchhoff-Carrier equation with n onlinear dissipation, Adv. Differential Equations, 6 (2001), 701-730
2001
-
[11]
C. Chen, Y. Kuo, T. Wu, The Nehari manifold for a Kirchhoff type problem involving sign-changing weight functions, J. Differential E quations., 250 (2011), 1876-1908
2011
-
[12]
B. T. Cheng, New existence and multiplicity of nontrivi al solutions for nonlocal elliptic Kirchhoff type problems, J. Math. Anal. Appl., 394 ( 2012), 488-495
2012
-
[13]
Chipot, B
M. Chipot, B. Lovat, Some remarks on nonlocal elliptic a nd parabolic problems, Nonlinear Anal., 30 (1997), 4619-4627
1997
-
[14]
Chipot, J
M. Chipot, J. F. Rodrigues, On a class of nonlocal nonlin ear elliptic problems, RAIRO Mod´elisation Math. Anal. Num´er., 26 (1992), 447-467
1992
-
[15]
N. T. Chung, An existence result for a class of Kirchhoff t ype systems via sub and supersolutions method, Appl. Math. Lett., 35 (2014), 95-10 1
2014
-
[16]
Q. Y. Dai, Y. G. Gu, Positive solutions for non-homogene ous semilinear elliptic equations with data that changes sign, Proc. Royal Soc. Edin burgh, (2003)133A, 297-306. 24
2003
-
[18]
Q. Y. Dai, L. H. Peng, Necessary and sufficient conditions for the existence of nonnegative solutions of inhomogeneous p-Laplace equatio n, Acta Math. Sci., 27 (2007), 34-56
2007
-
[19]
Q. Y. Dai, J. F. Yang, Positive solutions of inhomogeneo us elliptic equations with indefinite data, Nonlinear Anal., 58 (2004), 571-589
2004
-
[20]
D’Ancona, S
P. D’Ancona, S. Spagnolo, Global solvability for the de generate Kirchhoff equation with real analytic data, Invent. Math., 108 (1992), 247-262
1992
-
[21]
Y. B. Deng, Existence of multiple positive solution for −∆ u =λu +u N+2 N− 2 +µf (x), Acta Math. Sinica. 9 (1993), 311-320
1993
-
[22]
Y. B. Deng, Y. Li, Existence of bifurcation of the positi ve solutions for a semilinear equation with critical exponent, J.Differential Equations. 130 (1996), 179-200
1996
-
[23]
Y. B. Deng, S. Peng, W. Shuai, Existence and asymptotic b ehavior of nodal solutions for the Kirchhoff-type problem in R3, J. Funct. Anal. 269 (2015), no. 54, 3500-3527
2015
-
[24]
Drabek, J
P. Drabek, J. Hernandez, Existence and uniqueness of po sitive solutions for some quasilinear elliptic problems, Nonlinear Anal. TMA., 44 (2 001), 189-204
-
[25]
D. G. Figueiredo, P. L. Lions and R. D. Nussbaum, A priori estimates and exis- tence of positive solutions of semilinear elliptic equatio ns, J. Math. Pures Appl., 61 (1982), 41-63
1982
-
[26]
G. M. Figueiredo, Existence of a positive solution for a Kirchhoff problem type with critical growth via truncation argument, J. Math. Anal . Appl., 401 (2013), 706-713
2013
-
[27]
G. M. Figueiredo, A. Suarez, Some remarks on comparison principle in Kirchhoff equations, arXiv:1510.02151v1, 7 Oct 2015
2015 arXiv
-
[28]
X. M. He, W. M. Zou, Existence and concentration behavio r of positive solutions for a Kirchhoff equation in R3, J.Differential Equations. 252 (2012), 1813-1834
2012
-
[29]
Kirchhoff, Mechanik, Teubner, Leipzig, 1883
G. Kirchhoff, Mechanik, Teubner, Leipzig, 1883
-
[30]
Z. P. Liang, F. Y. Li, J. P. Shi, Positive solitions to Kir chhoff type equations with nonlinearity having prescribed asymptotic behavior, Ann. Inst. H. Poincar´e Anal NonLin´ear., 31 (2014), 155-167
2014
-
[31]
J. L. Lions, On some questions in boundary value problem s of mathemat- ical physics, in: Contemporary Developments in Continuum M echanics and Partial Differential Equations, Proceedings of Internation al Symposium, Inst. Mat. Univ. Fed Rio de Janeiro, Rio de Janeiro, 1977, in...
1977
-
[32]
A. M. Mao, Z. T. Zhang, Sign-changing and multiple solut ions of Kirchhoff type problems without the P.S.condition, Nonlinear Anal., 70 (2 009), 1275-1287
-
[33]
Naimen, The critical problem of Kirchhoff type ellipt ic equations in dimension four, J
D. Naimen, The critical problem of Kirchhoff type ellipt ic equations in dimension four, J. Differential Equations, 257 (2014), 1168-1193
2014
-
[34]
Naimen, Positive solutions of Kirchhoff type ellipti c equations involving a crit- ical Sobolev exponent, Nonlinear Differential Equations App l., 21 (2014), 885-914
D. Naimen, Positive solutions of Kirchhoff type ellipti c equations involving a crit- ical Sobolev exponent, Nonlinear Differential Equations App l., 21 (2014), 885-914
2014
-
[35]
Perera, Z
K. Perera, Z. T. Zhang, Nontrivial solutions of Kirchho ff-type problems via the Yang-index, J.Differential Equations, 221(2006), 246-255
2006
-
[36]
Rabinowitz, Multiple critical points of perturbed s ymmetric functionals, Trans
P. Rabinowitz, Multiple critical points of perturbed s ymmetric functionals, Trans. Amer. Math. Soc., 272 (1982), 753-769
1982
-
[37]
Shuai, Sign-changing solutions for a class of Kirchh off-type problem in bounded domains, J.Differential Equations
W. Shuai, Sign-changing solutions for a class of Kirchh off-type problem in bounded domains, J.Differential Equations. 259 (2015) 1256-1274
2015
-
[38]
Struwe, Variational Methods, Springer-Verlag Berl in Heidelberg 1996
M. Struwe, Variational Methods, Springer-Verlag Berl in Heidelberg 1996
1996
-
[39]
J. J. Sun, C. L. Tang, Existence and multipicity of solut ions for Kirchhoff type equations, Nonlinear Anal., 74 (2011), 1212-1222
2011
-
[40]
Tanaka, Morse indices at critical points related to t he symmetric mountain pass theorem and application, Comm
K. Tanaka, Morse indices at critical points related to t he symmetric mountain pass theorem and application, Comm. PDE., 14(1) (1989), 99- 128
1989
-
[41]
Tarantello, On nonhomogeneous elliptic equations i nvolving critical Sobolev exponent, Ann
G. Tarantello, On nonhomogeneous elliptic equations i nvolving critical Sobolev exponent, Ann. Inst. H. Poincare Anal. NonLineaire., 9(3) ( 1992), 281-304
1992
-
[42]
C. F. Vasconcellos, On a nonlinear stationary problem i n unbounded domains, Rev. Mat. Univ. Complut. Madrid, 5(1992), 309-318
1992
-
[43]
Y. Wu, Y. Huang, Z. Liu, On a Kirchhoff type problem in RN , J. Math. Anal. Appl., 425 (2015), 548-564
2015
-
[44]
L. P. Xu, H. B. Chen, Nontrivial solutions for Kirchhoff-t ype problems with a parameter, J. Math. Anal. Appl., 433 (2016), 455-472
2016
-
[45]
Q. G. Zhang, H. R. Sun, J. J. Nieto, Positive solution for a superlinear Kirchhoff- type problem with a parameter, Nonlinear Anal., 95 (2014), 3 33-338
2014
-
[46]
Z. T. Zhang, Y. M. Sun, Existence and multiplicity of sol utions for nonlocal sys- tems with Kirchhoff type, arXiv:1410.6225
-
[47]
L. Zeng, C. L. Tang, Existence of a positive ground state solution for a Kirchhoff type problem involving a critical exponent, Ann. Polon. Mat h., 117(2) (2016),163- 180. 26
2016
Reviewed August 14, 2026 · model on record in the stance chip above.
Discussion (0). Continue with ORCID to comment.