Ngoc-Sang PhamProfessor of Economics · Université de Lorraine
Ngoc-Sang Pham / Research by topics

My research focuses on general equilibrium and financial markets, asset-price bubbles, economic growth and development, and mathematical economics. The publications below are organized by research area.

General equilibrium theory with and without financial constraints

  1. Pham, N.-S. (2026). The relationship between general equilibrium models with infinite-lived agents and overlapping generations models, and some applications. Mathematical Social Sciences 142 (2026) 102553.
  2. Le Van, C., Pham, N.-S. (2025). Equilibrium with non-convex preferences: some insights. Bulletin of Economic Research.
  3. Le, T., Le Van, C., Pham, N.-S.,  Saglam, C. (2024). Sperner's lemma and competitive equilibrium with incomplete financial markets, Economics Letters, volume 328, May2024, 111720.
  4. Le, T., Le Van, C., Pham, N.-S.,  Saglam, C. (2022). A Direct Proof of the Gale–Nikaido–Debreu Lemma Using Sperner’s Lemma, Journal of Optimization Theory and Applications 194, 1072–1080 (2022).
  5. Le Van, C., Pham, N.-S. (2020). Demand and equilibrium with inferior and Giffen behaviors, Mathematical Social Sciences, vol. 103,  p. 45-50 (2020).
  6. Bosi, S., Le Van, C., Pham, N.-S. (2018). Intertemporal equilibrium with heterogeneous agents, endogenous dividends and collateral constraints, Journal of Mathematical Economics, vol. 76, p. 1-20 (2018).
    • We provide a characterization to check whether a sequence is an equilibrium or not; transversality conditions are proved. We introduce a theory of valuation of an asset that can be used as input by many producers.
    • See our working paper version (PDF) with omitted proofs (last step of the proof of part 2 of Proposition 1).
  7. Le Van, C., Pham, N.-S. (2016). Intertemporal equilibrium with financial asset and physical capital, Economic Theory, vol. 62, p. 155-199 (2016). Working paper version (PDF)
    • We investigate the interaction between financial market and production sector, and rational bubbles of several assets.

Book chapters:

  1. Le Van, C., Nguyen, T.D.H, Pham, N.-S., Tran-Nam, B. (2018). A General Equilibrium Model in Which Consumption Takes Time. In B. Tran-Nam, M. Tawada and M. Okawa (Eds.), " Recent Developments in Normative Trade Theory and Welfare Economics ", Springer-Verlag (2018).

Rational bubbles of assets with dividends

(in general equilibrium models with infinite-lived agents and OLG models)

  1. Pham, N.-S., Toda, A. A. (2026). Comment on 'Asset Bubbles and Overlapping Generations' by Jean Tirole. Econometrica, Vol. 94, No. 3 (May, 2026), 1027-1044.
  2. Pham, N.-S. (2026). The relationship between general equilibrium models with infinite-lived agents and overlapping generations models, and some applications. Mathematical Social Sciences 142 (2026) 102553.
  3. Pham, N.-S (2023). Intertemporal equilibrium with physical capital and financial asset: role of dividend taxation, Mathematical Social Sciences, vol. 123, p. 95-104 (2023).
  4. Bosi, S., Ha-Huy, T., Pham, C.-T., Pham, N.-S. (2022). Ascendant altruism and asset price bubbles, International Journal of Economic Theory, vol. 18, Issue 4, p. 532-551 (2022). Working paper version
  5. Bosi, S., Le Van, C., Pham, N.-S. (2022). Real indeterminacy and dynamics of asset price bubbles in general equilibrium, **Journal of Mathematical Economics,**Volume 100, May 2022, 102651.
  6. Bosi, S., Ha-Huy, T., Pham, C.-T., Pham, N.-S. (2019). Rational bubbles in altruistic economies: when Tirole meets Ramsey, Economics Bulletin, vol. 39(2), p. 816-829 (2019).
  7. Bosi, S., Le Van, C., Pham, N.-S. (2018). Intertemporal equilibrium with heterogeneous agents, endogenous dividends and collateral constraints, Journal of Mathematical Economics, vol. 76, p. 1-20 (2018).
    • We provide a characterization to check whether a sequence is an equilibrium or not; transversality conditions are proved. We introduce a theory of valuation of an asset that can be used as input by many producers.
    • See our working paper version (PDF) with omitted proofs (last step of the proof of part 2 of Proposition 1).
  8. Bosi, S., Ha-Huy, T., Le Van, C., Pham, C.-T., Pham, N.-S. (2018). Financial bubbles and capital accumulation in altruistic economies, Journal of Mathematical Economics, vol. 75, p. 125-139 (2018). Working paper version (PDF).
    • We study the global dynamics of capital stocks and asset values as well as the interplay between them in an OLG model.
  9. Bosi, S., Le Van, C., Pham, N.-S. (2017). Asset bubbles and efficiency in a generalized two-sector model. Mathematical Social Sciences, vol. 88, p. 37–48 (2017). Working paper version (PDF)
  10. Le Van, C., Pham, N.-S. (2016). Intertemporal equilibrium with financial asset and physical capital, Economic Theory, vol. 62, p. 155-199 (2016). Working paper version (PDF)
    • We investigate the interaction between financial market and production sector, and rational bubbles of several assets.

Book chapters:

  1. Bosi, S., Le Van, C., Pham, N.-S. (2017). Rational land and housing bubbles in infinite-horizon economies. In: K. Nishimura, A. Venditti and N. Yannelis (eds), "Sunspots and Non-Linear Dynamics – Essays in honor of Jean-Michel Grandmont",  Series "Studies in Economic Theory", Springer-Verlag (2017). Working paper version (PDF).

Working papers:

  1. Bosi, S., Le Van, C., Pham, N.-S. (2025). To Bubble or Not to Bubble: Asset Price Dynamics and Optimality in OLG Economies. (R&R,  Journal of Mathematical Economics)
    • Version 1, August 05, 2025; Version 2, September 02, 2025.
  2. Pham, N.-S, Toda, A. A. (2026) Long-Run Behavior of Equilibrium in Tirole (1985)'s Model with Dividend-Paying Asset. (R&R,  Journal of Economic Theory)
    • Version 1:  27 Jan 2025

Macroeconomics and financial markets

  1. Le Van,  C., Pham, N.-S., Pham, T.K.C., Tran-Nam, B. (2026).  Governance, productivity and economic development. Journal of Public Economic Theory, Volume28, Issue 1 February 2026 e70099.
  2. Hai-Ha Pham & Ngoc-Sang Pham, 2024. Effects of Wariness on Economic Growth in Overlapping Generations Models.  Journal of Mathematical Economics, vol. 115, 103060.
  3. Pham, N.-S (2023). Intertemporal equilibrium with physical capital and financial asset: role of dividend taxation, Mathematical Social Sciences, vol. 123, p. 95-104 (2023).
  4. Pham, N.-S. and Pham, T.H. (2021). Effects of credit limit on efficiency and welfare in a simple general equilibrium model (with Hien Pham), International Journal of Economic Theory, vol. 17, p. 446-470 (2021).
  5. Bosi, S., Le Van, C., Pham, N.-S. (2018). Intertemporal equilibrium with heterogeneous agents, endogenous dividends and collateral constraints, Journal of Mathematical Economics, vol. 76, p. 1-20 (2018).
  6. Le Van, C., Pham, N.-S. (2016). Intertemporal equilibrium with financial asset and physical capital, Economic Theory, vol. 62, p. 155-199 (2016). Working paper version (PDF)
    • We investigate the interaction between financial market and production sector, and rational bubbles of several assets.
  7. Bosi, S., Pham, N.-S. (2016). Taxation, bubbles and endogenous growth. Economics Letters, vol. 143, p. 73-76, (2016). Working paper version (PDF).
    • We figure out the cases where bubbles may harm or promote economic growth. Fiscal policy plays a role.
  8. Acurio-Vasconez, V., Giraud, G.,  Mc Isaac, F., Pham, N.-S. (2015). The Effects of Oil Price Shocks in a New-Keynesian Framework with Capital Accumulation. Energy Policy, vol. 86, p. 844–854, (2015).
    • Working paper version (PDF) and Appendix (PDF)

Book chapters:

  1. Pham, N.-S. (2024). L’investissement Socialement Responsable : Principes et enjeux, in Laré, A. et Saadaoui, K Fiches de Développement durable et RSE : Rappels de cours et exercices corrigés, Ed. Ellipses, p. 294-308, fiche 25, juillet 2024. (in French)
  2. Le Van, C., Pham, N.-S. (2022). Why does productivity matter?. In: Le Van, C., Pham Hoang, V., Tawada, M. (eds) International Trade, Economic Development, and the Vietnamese Economy. New Frontiers in Regional Science: Asian Perspectives, vol 61. Springer, Singapore.

Working papers:

  1. Pham, N.-S., Toda, A. A. (2026) Long-Run Behavior of Equilibrium in Tirole (1985)'s Model with Dividend-Paying Asset. (R&R,  Journal of Economic Theory)
  2. Pham, H.H., Pham, N.-S. (2025). Wariness and Poverty Traps. (R&R, Macroeconomic Dynamics)
  3. Le Van,  C., Nguyen-Trong, T., Pham, N.-S., Pham, T.K.C. (2025).  From Balanced Growth to Innovation Cycles: A Solow-Type Semi-Endogenous Growth Model . (R&R, Mathematical Social Sciences)
  4. Pham, N.-S. (2025). (Non-Monotonic) Effects of Productivity and Credit Constraints on Equilibrium Aggregate Production in General Equilibrium Models with Heterogeneous Producers.

FDI and economic growth

  1. Nguyen-Huu, T.T., Pham N.-S. (2026). FDI versus R&D in an endogenous growth model. Journal of Public Economic Theory.
  2. Nguyen-Huu, T.T., Pham N.-S. (2024). FDI spillovers, New Industry Development, and Economic Growth. Journal of Public Economic Theory, Volume26, Issue1 February 2024, e12670.
  3. Nguyen-Huu, T.T., Pham, N.-S. (2018). Should the host country invest in a new industry?. **Revue Economique,**vol. 69, p. 29-65 (2018).
    • Working paper version (PDF) and final version (PDF)

Foreign aid and economic development

  1. Pham, N.-S., Pham, T.K.C. (2025). Climate aid and global environmental quality. Revue d'Economie du Développement, 2025/3-4 Vol. 33 , p. 165-171.
  2. Le Van, C., Pham, N.-S., Pham, T.K.C. (2023). Effects of development aid (grants and loans) on the economic dynamics of the recipient country. Mathematical Social Sciences, vol. 125, p. 101-112 (2023).
  3. Pham, N.-S., Pham, T.K.C. (2020). Effects of foreign aid on the recipient country's economic growth, Journal of Mathematical Economics, vol. 86, p. 52-68 (2020).
  4. Pham, N.-S., Pham, T.K.C. (2019). Foreign aid, recipient government's fiscal behavior, and economic growth, Economics Bulletin, vol. 39(4), p. 2457-2466 (2019).

Book chapters:

  1. Pham, N.-S., Pham, T. K.C. (2022). Allocation and Effectiveness of Foreign Aid: an Overview. In: Le Van, C., Pham Hoang, V., Tawada, M. (eds) International Trade, Economic Development, and the Vietnamese Economy. New Frontiers in Regional Science: Asian Perspectives, vol 61. Springer, Singapore.

Optimization and applied mathematics

  1. Bosi, S., Desmarchelier, D., Pham, N.-S. (2026) A note on first-order and transversality conditions in infinite-horizon continuous-time optimal control models. Economics Letters. (Accept without Revision.)
  2. Gourdel, P., Le Van, C., Pham, N.-S., Tran-Viet, C. (2026). Hartman-Stampacchia theorem, Gale-Nikaidô-Debreu lemma, and Brouwer and Kakutani fixed-point theorems. Journal of Optimization Theory and Applications, 209, 24 (2026).
  3. Le, T., Le Van, C., Pham, N.-S.,  Saglam, C. (2022). A Direct Proof of the Gale–Nikaido–Debreu Lemma Using Sperner’s Lemma, Journal of Optimization Theory and Applications 194, 1072–1080 (2022).
  4. Bonnel, H., Pham, N.-S. (2011). Nonsmooth optimization over the (weakly or properly) Pareto set of a linear-quadratic multi-objective control problem: Explicit optimality conditions. Journal of Industrial and Management Optimization, vol. 7, No. 4, p. 789-809, (2011).