Proposition: Multiplication Of Rational Cauchy Sequences

Let \((x_n)_{n\in\mathbb N}\) and \((y_n)_{n\in\mathbb N}\) be two rational Cauchy sequences. The multiplication of rational Cauchy Sequences can be defined based on the multiplication of rational numbers as follows: \[\begin{array}{cclc} (x_n)_{n\in\mathbb N}\cdot (y_n)_{n\in\mathbb N}&:=&(x_n\cdot y_n)_{n\in\mathbb N}\\ \end{array}\] i.e. the product of two rational Cauchy sequences is a new rational sequence, whose sequence members are the products of rational numbers being the corresponding members of the original two rational Cauchy sequences.

Moreover, the new rational sequence \((x_n\cdot y_n)_{n\in\mathbb N}\) is also a rational Cauchy sequence.

Proofs: 1

  1. Proposition: Multiplication of Rational Cauchy Sequences Is Associative
  2. Proposition: Multiplication of Rational Cauchy Sequences Is Commutative
  3. Proposition: Existence of Rational Cauchy Sequence of Ones (Neutral Element of Multiplication of Rational Cauchy Sequences)
  4. Proposition: Multiplication of Rational Cauchy Sequences Is Cancellative

Proofs: 1 2 3 4 5 6 7 8 9
Propositions: 10 11 12 13 14 15


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References

Bibliography

  1. Kramer Jürg, von Pippich, Anna-Maria: "Von den natürlichen Zahlen zu den Quaternionen", Springer-Spektrum, 2013