S. I. , Spaces of mappings into a manifold of negative curvature, Dokl. Akad. Nauk SSSR, vol.178, p.3, 1968.

A. D. Aleksandrov, A theorem on triangles in a metric space and some of its applications, In Trudy Mat. Inst. Steklov, vol.38, p.29, 1951.

P. Absil, R. Mahony, and R. Sepulchre, Optimization algorithms on matrix manifolds, p.30, 2008.

B. Afsari, R. Tron, and R. Vidal, On the convergence of gradient descent for finding the Riemannian center of mass, SIAM J. Control Optim, vol.51, issue.3, p.44, 2013.

S. Bartels, Stability and convergence of finite-element approximation schemes for harmonic maps, SIAM J. Numer. Anal, vol.43, issue.1, p.3, 2005.

S. Bartels, Numerical analysis of a finite element scheme for the approximation of harmonic maps into surfaces, Math. Comp, vol.79, issue.271, p.3, 2010.

S. Bartels, Numerical methods for nonlinear partial differential equations, Springer Series in Computational Mathematics. Springer, vol.47, p.3, 2015.

S. Bau, S. M. Gagola, and I. , Decomposition of closed orientable geometric surfaces into acute geodesic triangles, Arch. Math. (Basel), vol.110, issue.1, p.47, 2018.

R. Martin, A. Bridson, and . Haefliger, Metric spaces of non-positive curvature, Grundlehren der Mathematischen Wissenschaften, vol.319

. Springer-verlag, , p.29, 1999.

E. Andries, W. H. Brouwer, and . Haemers, Spectra of graphs. Universitext, p.13, 2012.

A. I. Bobenko, U. Pinkall, and B. A. Springborn, Discrete conformal maps and ideal hyperbolic polyhedra, Geom. Topol, vol.19, issue.4, p.18, 2015.

L. Brewin, Riemann normal coordinates, p.38, 1996.

L. Brewin, Riemann normal coordinate expansions using Cadabra, Classical Quantum Gravity, vol.26, issue.17, p.38, 2009.

A. I. Bobenko and Y. B. Suris, Discrete differential geometry, Graduate Studies in Mathematics, vol.98, p.3, 2008.

Y. Colin-de-verdière, Comment rendre géodésique une triangulation d'une surface?, Enseign. Math, vol.37, issue.2, p.3, 1991.

Y. , C. De-verdière, and A. Marin, Triangulations presque équilatérales des surfaces, J. Differential Geom, vol.32, issue.1, p.47, 1990.

J. Chen, On energy minimizing mappings between and into singular spaces, Duke Math. J, vol.79, issue.1, p.3, 1995.

D. Chiron, On the definitions of Sobolev and BV spaces into singular spaces and the trace problem, Commun. Contemp. Math, vol.9, issue.4, p.21, 2007.

R. K. Fan and . Chung, Spectral graph theory, CBMS Regional Conference Series in Mathematics. Published for the Conference Board of the Mathematical Sciences, vol.92, p.13, 1997.

K. Corlette, Flat G-bundles with canonical metrics, J. Differential Geom, vol.28, issue.3, pp.361-382, 1988.
DOI : 10.4310/jdg/1214442469

URL : https://doi.org/10.4310/jdg/1214442469

G. Dal-maso, An introduction to ?-convergence, of Progress in Nonlinear Differential Equations and their Applications, vol.8, 1993.

G. Daskalopoulos and C. Mese, Harmonic maps from a simplicial complex and geometric rigidity, J. Differential Geom, vol.78, issue.2, p.3, 2008.
DOI : 10.4310/jdg/1203000268

URL : https://doi.org/10.4310/jdg/1203000268

G. Daskalopoulos, C. Mese, and A. Vdovina, Superrigidity of hyperbolic buildings, Geom. Funct. Anal, vol.21, issue.4, p.3, 2011.
DOI : 10.1007/s00039-011-0124-9

URL : http://www.math.jhu.edu/%7Ecmese/superrigidity-hyperbolic-building-112909.pdf

S. K. Donaldson, Twisted harmonic maps and the self-duality equations, Proc. London Math. Soc, vol.55, issue.3, pp.127-131, 1987.
DOI : 10.1112/plms/s3-55.1.127

D. Georgios, R. A. Daskalopoulos, and . Wentworth, Harmonic maps and Teichmüller theory, Handbook of Teichmüller theory, vol.I, p.48, 2007.

J. Eells and B. Fuglede, Harmonic maps between Riemannian polyhedra, Cambridge Tracts in Mathematics, vol.142, pp.3-14, 2001.

J. Eells and J. H. Sampson, Harmonic mappings of Riemannian manifolds, Amer. J. Math, vol.86, p.20, 1964.
DOI : 10.2307/2373037

O. P. Ferreira, M. S. Louzeiro, and L. F. Prudente, Gradient method for optimization on riemannian manifolds with lower bounded curvature, p.31, 2018.

B. Fuglede, Homotopy problems for harmonic maps to spaces of nonpositive curvature, Comm. Anal. Geom, vol.16, issue.4, p.3, 2008.
DOI : 10.4310/cag.2008.v16.n4.a1

URL : http://www.intlpress.com/site/pub/files/_fulltext/journals/cag/2008/0016/0004/CAG-2008-0016-0004-a001.pdf

C. Friedrich and G. , Allgemeine auflösung der aufgabe: die theile einer gegebenen fläche auf einer andern gegebenen fläche so abzubilden, dass die abbildung dem abgebildeten in den kleinisten theilen ähnlich wird, Astronomische Abhandlungen, vol.3, p.10

S. Gallot, D. Hulin, and J. Lafontaine, Riemannian geometry, p.7, 2004.
URL : https://hal.archives-ouvertes.fr/hal-00002870

J. Gaster, B. Loustau, and L. Monsaingeon, Computing equivariant harmonic maps, p.47
URL : https://hal.archives-ouvertes.fr/hal-02054982

C. Godsil and G. Royle, Algebraic graph theory, Graduate Texts in Mathematics, vol.207, p.13, 2001.

M. Gromov and R. Schoen, Harmonic maps into singular spaces and p-adic superrigidity for lattices in groups of rank one, Inst. Hautes Études Sci. Publ. Math, issue.76, pp.165-246, 1992.

W. Huang, P. Absil, K. A. Gallivan, and P. Hand, Roptlib: an object-oriented c++ library for optimization on riemannian manifolds, p.30, 2016.

P. Hartman, On homotopic harmonic maps, Canad. J. Math, vol.19, pp.673-687, 1967.
DOI : 10.4153/cjm-1967-062-6

N. J. Hitchin, The self-duality equations on a Riemann surface, Proc. London Math. Soc, vol.55, issue.3, p.3, 1987.
DOI : 10.1112/plms/s3-55.1.59

J. Hass and P. Scott, Simplicial energy and simplicial harmonic maps, Asian J. Math, vol.19, issue.4, p.3, 2015.
DOI : 10.4310/ajm.2015.v19.n4.a2

URL : https://www.math.ucdavis.edu/%7Ehass/Research/Papers/PLEnergy3.pdf

H. Izeki and S. Nayatani, Combinatorial harmonic maps and discrete-group actions on Hadamard spaces, Geom. Dedicata, vol.114, pp.147-188, 2005.

J. Jost, Harmonic mappings between Riemannian manifolds, Proceedings of the Centre for Mathematical Analysis, vol.4, p.3, 1984.

J. Jost, Equilibrium maps between metric spaces, Calc. Var. Partial Differential Equations, vol.2, pp.173-204, 1994.

J. Jost, Convex functionals and generalized harmonic maps into spaces of nonpositive curvature, Comment. Math. Helv, vol.70, issue.4, pp.659-673, 1995.

J. Jost, Generalized harmonic maps between metric spaces, Geometric analysis and the calculus of variations, p.17, 1996.

J. Jost, Nonpositive curvature: geometric and analytic aspects, Lectures in Mathematics ETH Zürich. Birkhäuser Verlag, p.40, 1997.

J. Jost, Riemannian geometry and geometric analysis, p.41, 2017.

J. Jost and L. Todjihounde, Harmonic nets in metric spaces, Pacific J. Math, vol.231, issue.2, p.44, 2007.

H. Karcher, Riemannian center of mass and mollifier smoothing, Comm. Pure Appl. Math, vol.30, issue.5, p.35, 1977.

A. Kriegl and P. W. Michor, The convenient setting of global analysis, Mathematical Surveys and Monographs, vol.53, p.7, 1997.

C. Kourouniotis, Complex length coordinates for quasi-Fuchsian groups, Mathematika, vol.41, issue.1, p.47, 1994.

J. Nicholas, R. M. Korevaar, and . Schoen, Sobolev spaces and harmonic maps for metric space targets, Comm. Anal. Geom, vol.1, issue.3-4, p.35, 1993.

J. Nicholas, R. M. Korevaar, and . Schoen, Global existence theorems for harmonic maps to non-locally compact spaces, Comm. Anal. Geom, vol.5, issue.2, pp.333-387, 1997.

M. Kotani and T. Sunada, Standard realizations of crystal lattices via harmonic maps, Trans. Amer. Math. Soc, vol.353, issue.1, p.3, 2001.

F. Labourie, Existence d'applications harmoniques tordues à valeurs dans les variétés à courbure négative, Proc. Amer. Math. Soc, vol.111, issue.3, p.10, 1991.

É. Lebeau, Applications harmoniques entre graphes finis et un théorème de superrigidité, Séminaire de Théorie Spectrale et Géométrie, vol.14, p.3, 1995.

B. Maskit, Matrices for Fenchel-Nielsen parameters in genus 2, Complex geometry of groups, vol.240, p.47, 1998.

B. Maskit, Matrices for Fenchel-Nielsen coordinates, Ann. Acad. Sci. Fenn. Math, vol.26, issue.2, p.47, 2001.

C. Mese, Uniqueness theorems for harmonic maps into metric spaces, Commun. Contemp. Math, vol.4, issue.4, p.22, 2002.

U. Pinkall and K. Polthier, Computing discrete minimal surfaces and their conjugates, Experiment. Math, vol.2, issue.1, pp.15-36, 1993.

J. G. Ratcliffe, Foundations of hyperbolic manifolds, Graduate Texts in Mathematics, vol.149, p.23, 2006.

. Raziel, Square of the distance function on a riemannian manifold (answer), p.40, 2015.

B. R. Bernhard-riemann, Über die Hypothesen, welche der Geometrie zu Grunde liegen". Klassische Texte der Wissenschaft

S. Spektrum, Historical and mathematical commentary by Jürgen Jost, p.38, 2013.

A. S. Sikora, Character varieties, Trans. Amer. Math. Soc, vol.364, issue.10, p.10, 2012.

C. T. Simpson, Nonabelian Hodge theory, Proceedings of the International Congress of Mathematicians, vol.I, p.3, 1990.

S. Yum-tong, The complex-analyticity of harmonic maps and the strong rigidity of compact Kähler manifolds, Ann. of Math, vol.112, issue.2, p.3, 1980.

C. Udri?te, Convex functions and optimization methods on Riemannian manifolds, p.31, 1994.

M. Wang, Generalized harmonic maps and representations of discrete groups, Comm. Anal. Geom, vol.8, issue.3, pp.545-563, 2000.

T. J. Willmore, Mean value theorems in harmonic Riemannian spaces, J. London Math. Soc, vol.25, p.36, 1950.

M. Wolf, The Teichmüller theory of harmonic maps, J. Differential Geom, vol.29, issue.2, p.48, 1989.

C. T. Zamfirescu, Survey of two-dimensional acute triangulations, Discrete Math, vol.313, issue.1, p.47, 2013.

H. Zhang and S. Sra, First-order methods for geodesically convex optimization, p.31, 2016.