7h

revised 
Primary structures in $\mathbb Q$
typo 
7h

comment 
Primary structures in $\mathbb Q$
@EmilJeřábek, thank you for answering my just in case questions. For the sake of the completeness of the thread you may still enter your text as an Answer, including your observation about the maximality of the primary structures. Question Q2 is still the key. 
1d

revised 
Primary structures in $\mathbb Q$
1line intro 
1d

revised 
Primary structures in $\mathbb Q$
a math typo 
1d

revised 
Primary structures in $\mathbb Q$
a trivial typo 
1d

answered  Primary structures in $\mathbb Q$ 
1d

revised 
Primary structures in $\mathbb Q$
triviality (same sense) 
1d

comment 
Primary structures in $\mathbb Q$
@EmilJeřábek, thank you for pointing to my typos. I've fixed them by now. It was not just $\ S\ $ but the induced multiplicative monoid $\ S^*;\ $ and it was also supposed to be an additive semigroup  not an additive monoid. Sorry for the typos. 
1d

revised 
Primary structures in $\mathbb Q$
Typo! Bad :) 
1d

revised 
Primary structures in $\mathbb Q$
italic 
1d

revised 
Primary structures in $\mathbb Q$
typo 
1d

comment 
Primary structures in $\mathbb Q$
I could add examples of u.d.p. sequences for which it is not obvious that they are not additive monoids (i.e. that they are not primary structures). The QUESTION is already a bit long but I could do it. 
1d

asked  Primary structures in $\mathbb Q$ 
Feb
6 
comment 
What (fun) results in graph theory should undergraduates learn?
@FedorPetrov, perhaps you are right but then we need a separate subforum for such questions. 
Feb
4 
revised 
natural radical and an algebraic expression in $\pi$ and/or $e$
parentheses 
Feb
4 
revised 
natural radical and an algebraic expression in $\pi$ and/or $e$
LaTeX 
Feb
4 
revised 
natural radical and an algebraic expression in $\pi$ and/or $e$
typos 
Feb
3 
comment 
natural radical and an algebraic expression in $\pi$ and/or $e$
@Wojowu, thank you. (About the "need"I can't help it :). 
Feb
3 
comment 
natural radical and an algebraic expression in $\pi$ and/or $e$
Great @Wojowu, thank you, what a relief! May I absorb your superstep into the Addendum to the "QUESTION"? (I'd credit you, but of course). 
Feb
3 
revised 
natural radical and an algebraic expression in $\pi$ and/or $e$
a typo 