14th
Direct and semi-direct
Today I transcended my existence in human form. I am now a being of pure logic. But apparently even beings of pure logic still like to ride their bikes and sit in the park; they just have to do math at the same time. So it’s not so bad.
One fun thing for the day: semidirect products. Like direct products, but less so. And a way of making non-abelian groups. Basically you take two groups A and B and make a group of all the pairs (a,b) with a in A and b in B, but instead of setting the multiplication up so that ‘a’s and ‘b’s commute with each other, you set it up so that each a acts on B (by conjugation) as some particular automorphism. That is, (a)(b)(a inverse) gives you some other element of B in a neat and coherent way.
Also upon reflection the e. e. cummings poem is for sure about sex.
