PrefaceIntroduction1 Dimensional Analysis, Modeling, and Invariance1.1 Introduction1.2 Dimensional Analysis: Buckingham Pi-Theorem1.2.1 Assumptions Behind Dimensional Analysis1.2.2 Conclusions from Dimensional Analysis1.2.3 Proof of the Buckingham Pi-Theorem1.2.4 Examples1.3 Application of Dimensional Analysis to PDEs1.3.1 Examples1.4 Generalization of Dimensional Analysis: Invariance of PDEs Under Scalings of Variables1.5 Discussion2 Lie Groups of Transformations and Infinitesimal Transformations2.1 Introduction2.2 Lie Groups of Transformations2.2.1 Groups2.2.2 Examples of Groups2.2.3 Group of Transformations2.2.4 One-Parameter Lie Group of Transformations2.2.5 Examples of One-Parameter Lie Groups of Transformations2.3 Infinitesimal Transformations2.3.1 First Fundamental Theorem of Lie2.3.2 Examples Illustrating' Lie's First Fundamental Theorem2.3.3 Infinitesimal Generators2.3.4 Invariant Functions2.3.5 CanonicaI Coordinates2,3.6 Examples of Sets of Canonical Coordinates2.4 Point Transformations and Extended Transformations (Prolongations)2.4.1 Extended Group of Point Transformations: One Dependent and One Independent Variable2.4.2 Extended Infinitesimal Transformations: One Dependent and One Independent Variable2.4.3 Extended Transformations: One Dependent and n Independent Variables2.4.4 Extended Infinitesimal Transformations: One Dependent and n Independent Variables2.4.5 Extended Transformations and Extended Infinitesimal Transformations: m Dependent and n Independent Variables2.5 Multi parameter Lie Groups of Transformations and Lie Algebras2.5.1 r-Parameter Lie Groups of Transformations2.5.2 Lie Algebras2.5.3 Examples of Lie Algebras2.5.4 Solvable Lie Algebras2.6 Mappings of Curves and Surfaces2.6.1 Invariant Surfaces, Invariant Curves, Invariant Points2.6.2 Mappings of Curves2.6.3 Examples of Mappings of Curves2.6.4 Mappings of Surfaces2.7 Local Transformations2.7.1 Point Transformations2.7.2 Contact and Higher-Order Transformations2.7.3 Examples of Local Transformations2.8 Discussion3 Ordinary Differential Equations (ODEs)3.1 Introduction3.1.1 Elementary Examples3.2 First-Order ODEs3.2.1 CanonicaI Coordinates3.2.2 Integrating Factors3.2.3 Mappings of Solution Curves3.2.4 Determining Equation for Symmetries of a First-Order ODE3.2.5 Determination of First-Order ODEs Invariant Under a Given Group3.3 Invariance of Second- and Higher-Order ODEs Under Point Symmetries3.3.1 Reduction of Order Through CanonicaI Coordinates3.3.2 Reduction of Order Through Differential lnvariants3.3.3 Examples of Reduction of Order3.3.4 Determining Equations for Point Symmetries of annth-Order ODE3.3.5 Determination of nth-Order ODEs Invariant Under a Given Group……4 Partial Differential Equations (PDEs)