Why is 1 + 1 = 2 ?

Wuu Yang. Why is 1 + 1 = 2 ?. J. Inf. Sci. Eng., 18(3):281-310, 2002. [doi]

@article{Yang02b,
  title = {Why is 1 + 1 = 2 ?},
  author = {Wuu Yang},
  year = {2002},
  url = {http://www.iis.sinica.edu.tw/page/jise/2002/200203_07.html},
  researchr = {https://researchr.org/publication/Yang02b},
  cites = {0},
  citedby = {0},
  journal = {J. Inf. Sci. Eng.},
  volume = {18},
  number = {3},
  pages = {281-310},
}