---
name: "nauty-twohamg"
section: "1"
platform: "linux"
package: "nauty"
version: "2.8.9+ds-1+b1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/nauty-twohamg"
---

# nauty-twohamg(1)

split quartic graphs into two hamiltonian cycles

## NAME

nauty-twohamg - split quartic graphs into two hamiltonian cycles

## SYNOPSIS

**twohamg** \[*-sgvq*\] \[*-L#*\] \[*infile* \[*outfile*\]\]

## DESCRIPTION

-

  Partition quartic graphs into two hamiltonian cycles.

-

  Output those which cannot be partitioned.

- **-s**

  force output to sparse6 format

- **-g**

  force output to graph6 format If neither **-s** or **-g** are given, the output format is determined by the header or, if there is none, by the format of the first input graph. Also see **-S**.

-

  The output file will have a header if and only if the input file does.

- **-p**

  Read a cubic graph and use its prism. Vertex i of the input becomes

-

  vertices 2\*i,2\*i+1 in the prism.

- **-x**

  Test for decompositions using each 2-path

- **-X**

  As **-x** but only output if two 2-paths are missed at some vertex

- **-y**

  Test for decompositions using each non-triangular 3-path

**-t**# With **-x** and **-X**, consider only paths with center #

-

  With **-y**, consider only paths starting at #

- **-Y**

  With **-p**, only consider paths whose central edge is vertical

- **-v**

  Give a partition for those graphs who have one and a message for those which don't. With **-x**, list exceptional 2-paths.

**-L**# Limit to 1000\*# iterations; write with message if timeout.

-

  Graphs that time out are written to the output.

- **-q**

  suppress auxiliary information