Consider a set $F$ which is both monoid (with identity $1$ and composition $\circ$) and complete lattice with join $\bigsqcup$ and order $\leq$.
Let the following identities hold:
- $(a\circ b)\sqcup c=(a\circ c)\sqcup(b\circ c)$;
- $c\sqcup(a\circ b)=(c\circ a)\sqcup(c\circ b)$.
Let $\mu\in F$.
I name the minimal reflexive ($x\geq 1$) transitive ($x\circ x\leq x$) element $x$ which is above $\mu$ as transitive closure of $\mu$.
Are the following statements necessarily true?
Transitive closure of $\mu$ exists.
Transitive closure is the recursively defined set with elements defined as:
- $1$;
- $\mu$;
- composition of other elements of the set;
- finite and infinite (countable) joins of other elements of the set.