Bounding the largest inhomogeneous Diophantine approximation constant
dc.contributor.author | Paudel, Bishnu | |
dc.date.accessioned | 2024-05-21T20:52:58Z | |
dc.date.available | 2024-05-21T20:52:58Z | |
dc.date.graduationmonth | August | |
dc.date.published | 2024 | |
dc.description.abstract | For 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.advisor | Christopher G. Pinner | |
dc.description.degree | Doctor of Philosophy | |
dc.description.department | Department of Mathematics | |
dc.description.level | Doctoral | |
dc.identifier.uri | https://hdl.handle.net/2097/44364 | |
dc.language.iso | en_US | |
dc.subject | Inhomogeneous Diophantine approximation, negative continued fraction expansion, alpha-expansion of gamma | |
dc.title | Bounding the largest inhomogeneous Diophantine approximation constant | |
dc.type | Dissertation |