Monday, May 14, 2018

elementary set theory - Equinumerousity of operations on cardinal numbers

I want to prove for all Cardinal numbers a, b, c that:




  1. (ab)c=cacbc




  2. a(b+c)=cabac




  3. (ab)c=cabc



I know that for 1. it's enough to show that (ca×b)=c(ca)×(cb) because my teacher told me so.


I think that I have to show the relation "" first and then "" by finding an injective function in both cases. For the latter I'm thinking that for every (f1f2)(ca) x (cb) let f:ca x b be defined as f(x)=(f1(x),f2(x)) which gives the injective function (f1f2)f but I don't know how to verify. For "" I tried to do it the other way around but it makes no sense..

No comments:

Post a Comment

analysis - Injection, making bijection

I have injection f:AB and I want to get bijection. Can I just resting codomain to f(A)? I know that every function i...