On a certain problem of Ulam and its generalization
Author(s) -
Anup Biswas
Publication year - 2010
Publication title -
elemente der mathematik
Language(s) - English
Resource type - Journals
eISSN - 1420-8962
pISSN - 0013-6018
DOI - 10.4171/em/147
Subject(s) - generalization , mathematics , mathematical economics , algebra over a field , calculus (dental) , pure mathematics , mathematical analysis , orthodontics , medicine
Let N be the set of all positive integers with usual operations a + b ≡ s(a, b) (addition) and a ∗ b ≡ m(a, b) (multiplication). For every bijection p : N × N → N define two mappings σ and μ from N to N such that σ(c) = σ(p(a, b)) = s(a, b) and μ(c) = μ(p(a, b)) = m(a, b) for all c ∈ N. Such a bijection p is known as Peano mapping. In [1, p. 32] S.M. Ulam asked “Does there exist a Peano mapping p such that addition commutes with multiplication in the sense that σ(μ(c)) = μ(σ(c)) for all c ∈ N ?”. No examples were known, and then the well-known Peano mapping p(a, b) = 2a−1(2b − 1) was seen by Ulam not to work, as μ(σ(2)) = μ(3) = 2, σ(μ(2)) = σ(2) = 3. Though the question is very natural and fascinating, it never got an answer since then.
Accelerating Research
Robert Robinson Avenue,
Oxford Science Park, Oxford
OX4 4GP, United Kingdom
Address
John Eccles HouseRobert Robinson Avenue,
Oxford Science Park, Oxford
OX4 4GP, United Kingdom