Bounding the largest inhomogeneous Diophantine approximation constant

dc.contributor.authorPaudel, Bishnu
dc.date.accessioned2024-05-21T20:52:58Z
dc.date.available2024-05-21T20:52:58Z
dc.date.graduationmonthAugust
dc.date.published2024
dc.description.abstractFor an irrational real α and real γ ∉ αZ + Z, one defines the two-sided inhomogeneous approximation constant M(α,γ):= liminf_{|n|→∞} |n| ||nα-γ||, and the worst-case of inhomogeneous approximation ρ(α):=sup_{ γ ∉ αZ + Z} M(α,γ). By a well-known theorem of Minkowski, we have ρ(α) ≤ 1/4. This dissertation focuses on bounding ρ(α) in terms of R:=liminf_{i→∞} aᵢ, where aᵢ are the partial quotients in the negative (i.e. the `round-up') continued fraction expansion α. We prove that if R is odd, then the upper bound 1/4 can be replaced by 1/4(1-1/R)(1-1/R²), which is optimal. The optimal upper bound for even R≥ 4 was already known. We also obtain bounds of the form ρ(α)≥ C(R) for any R≥ 3 which are best possible when R is even (and asymptotically precise when R is odd). In particular, ρ(α) ≥ 1/(6√3+8)=1/18.3923..., when R=3, 1/(4√3+2)=1/8.9282…, when R≥4.
dc.description.advisorChristopher G. Pinner
dc.description.degreeDoctor of Philosophy
dc.description.departmentDepartment of Mathematics
dc.description.levelDoctoral
dc.identifier.urihttps://hdl.handle.net/2097/44364
dc.language.isoen_US
dc.subjectInhomogeneous Diophantine approximation, negative continued fraction expansion, alpha-expansion of gamma
dc.titleBounding the largest inhomogeneous Diophantine approximation constant
dc.typeDissertation

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