C. Lang

activity

20132021

most citedFibonacci Numbers and Identities II

7 citations · 11 across the 15 of their papers we have counts for

collaborators

16 papers

math.CO2021

Fibonacci identities and Fibonacci pairs

Cheng Lien Lang, Mong Lung Lang

A Fibonacci pair $F_{s} (w, x)$ of rank $s$ is a pair $s \times s$ nonsingular matrices such that $w x = x w$ and that the entries of $a w^{n}$ and $a x w^{m}$ are polynomials of Fibonacci or Luc…

math.GR2015

Arithmetic and geometry of the Hecke groups

Cheng Lien Lang, Mong Lung Lang

We study the arithmetic and geometry properties of the Hecke group $G_{q}$ . In particular, we prove that $G_{q}$ has a subgroup $X$ of index $d$ , genus $g$ with $v_{\infty}$ cusps, a…

math.NT2015

Identifying normal and congruence subgroups

Cheng Lien Lang, Mong Lung Lang

We give a simple algorithm that enables us to determine whether a subgroup of finite index of the Hecke group is normal.

math.NT2014

Wohlfahrt's Theorem and index formula for elementary matrix groups and $S L (2, O)$

Cheng Lien Lang, Mong Lung Lang

The present article determines the indices of the principal congruence subgroups of the Bianchi groups $B_{d}$ , $S L (2, O)$ and elementary matrix group $E$ and extends Wohlfah…

math.GR2014

Commutator subgroup of the Hecke group $G_{5}$ is not congruence

Cheng Lien Lang, Mong Lung Lang

We prove that the power subgroup $G_{5}^{5}$ and the commutator subgroup $G_{5}^{'}$ of the Hecke group $G_{5}$ are not congruence.

math.GR2014★ 2 cited

Wohlfahrt's Theorem for the Hecke group G_5

Cheng Lien Lang, Mong Lung Lang

Let K be a subgroup of the inhomogeneous Hecke group G_5 of finite index. Suppose that the geometric level of K is r. Then K is congruence if and only if K contains the principal c…

Fibonacci identities and Fibonacci pairs

Arithmetic and geometry of the Hecke groups

Identifying normal and congruence subgroups

Wohlfahrt's Theorem and index formula for elementary matrix groups and SL(2,O)

Commutator subgroup of the Hecke group G5​ is not congruence

Wohlfahrt's Theorem for the Hecke group G_5

Wohlfahrt's Theorem and index formula for elementary matrix groups and $S L (2, O)$

Commutator subgroup of the Hecke group $G_{5}$ is not congruence