published_or_final_version / Mathematics / Master / Master of Philosophy

Let f : S → S(^4) be an immersion of a Riemann surface in the 4-sphere. The thesis begins with a study of the adapted moving frame of / in order to produce conditions for certain naturally defined lifts to SO(5)/U(2) and S0(5)T(^2) to be conformal, harmonic and holomorphic with respect to two different but naturally occuring almost complex structures. This approach brings together the results of a number of authors regarding lifts of conformal, minimal immersions including the link with solutions of the Toda equations. Moreover it is shown that parallel mean curvature immersions have haj-monic lifts into S0(5)/U(2).A certain natural lift of / into CP(^3), the twistor space of S(^4), is studied more carefully via an explicit description and in the case of / being a conformal immersion this gives a beautiful and simple formula for the lift in terms of a stereographic co-ordinate associated to /. This involves establishing explicitly the two-to-one correspondence between elements of the matrix groups Sp(2) and SO(5) and working with quaternions. The formula enables properties of such lifts to be explored and in particular it is shown that the harmonic sequence of a harmonic lift is either finite or satisfies a certain symmetry property. Uniqueness properties of harmonic lifts are also proved. Finally, the ideas are extended to the hyperbolic space H(^4) and after an exposition of the twistor fibration for this case, a method for constructing superminimal immersions of surfaces into H'^ from those in S"' is given.

Univ., Diss.--Sendai.

Thesis (M. Phil.)--University of Hong Kong, 1997. / Includes bibliographical references (leaf 61-66).

Thesis (doctoral)--Rheinische Friedrich-Wilhelms-Universität Bonn, 2004. / Includes bibliographical references (p. 98-100).

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Hung Ling Yan Lincoln. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 87-88). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.5 / Chapter 2 --- Preliminary --- p.10 / Chapter 2.1 --- Background in geometry --- p.10 / Chapter 2.2 --- Background in harmonic maps --- p.12 / Chapter 3 --- Lie Point Transformations and Symmetries --- p.16 / Chapter 3.1 --- Definition of symmetries --- p.16 / Chapter 3.2 --- Determine the Lie point symmetries of partial differential equations --- p.25 / Chapter 3.2.1 --- Second order differential equations --- p.26 / Chapter 4 --- Similarity Variables --- p.30 / Chapter 4.1 --- "Similarity variables and group-invariant, solutions" --- p.30 / Chapter 4.2 --- Reduction of number of variables of the partial differential equations --- p.34 / Chapter 4.2.1 --- Determine the similarity variables --- p.34 / Chapter 4.2.2 --- Procedure to reduce the number of variables of a system of partial differential equations --- p.36 / Chapter 5 --- Group Invariant Harmonic Maps --- p.38 / Chapter 5.1 --- Determine the Lie point symmetries of the harmonic map equations --- p.39 / Chapter 5.2 --- Reduction of harmonic map equations to ordinary differ- ential equations --- p.54 / Chapter 5.3 --- Solving the harmonic map system which has been reduced to ordinary differential equations --- p.62 / Chapter 5.3.1 --- Case 1 of Theorem 5.2.1 --- p.62 / Chapter 5.3.2 --- Case 2 of Theorem 5.2.1 --- p.66 / Chapter 5.3.3 --- Case 3 of Theorem 5.2.1 --- p.75 / Bibliography --- p.87

Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Mathematics." Includes bibliographical references (p. 51-52).

Thesis (M. Phil.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 112-116).

published_or_final_version / Mathematics / Master / Master of Philosophy