A characterization of rational elements by Lüroth-type series expansions in the p-adic number field and in the field of Laurent series over a finite field
The Littlewood conjecture in Diophantine approximation claims thatholds for all real numbers and , where denotes the distance to the nearest integer. Its -adic analogue, formulated by de Mathan and Teulié in 2004, asserts thatholds for every real number and every prime number , where denotes the -adic absolute value normalized by . We survey the known results on these conjectures and highlight recent developments.