cmima -mim-cmi- gismu

x1 is a member/element of set x2; x1 belongs to group x2; x1 is amid/among/amongst group x2.

x1 may be a complete or incomplete list of members; x2 is normally marked by la'i/le'i/lo'i, defining the set in terms of its common property(ies), though it may be a complete enumeration of the membership. See also ciste, porsi, jbini, girzu, gunma, klesi, cmavo list mei, kampu, lanzu, liste.

In notes:

ciste
x1 (mass) is a system interrelated by structure x2 among components x3 (set) displaying x4 (ka).
girzu
x1 is group/cluster/team showing common property (ka) x2 due to set x3 linked by relations x4.
gunma
x1 is a mass/team/aggregate/whole, together composed of components x2, considered jointly.
jbini
x1 is between/among set of points/bounds/limits x2 (set)/amidst mass x2 in property x3 (ka).
kampu
x1 (property - ka) is common/general/universal among members of set x2 (complete set).
klesi
x1 (mass/si'o) is a class/category/subgroup/subset within x2 with defining property x3 (ka).
lanzu
x1 (mass) is a family with members including x2 bonded/tied/joined according to standard x3.
liste
x1 (physical object) is a list/catalog/register of sequence/set x2 in order x3 in medium x4.
porsi
x1 [ordered set] is sequenced/ordered/listed by comparison/rules x2 on unordered set x3.
mei
convert number to cardinality selbri; x1 is a mass formed from a set x2 of n members, one or more of which is/are x3, measured relative to the set x4.
cmibi'o
b1=c1 becomes a member of group b2=c2 under conditions b3.
cmigau
g1 puts together c1 into group c2.
cmimei
x1 (collection/sequence) has x2 (number) members
cmisau
s1=c1 is logged into system/application s2=c2.
cmiveigau
g1=v3 registers c1 as a member of c2, registration preserved in medium x3=v4.
cu'acmi
cm1=cu1 is a member of electorate cm2, which votes/selects cu2 [choice] from set/sequence of alternatives cu3.
jutcmi
x1 (organism) is a member of species x2, genus x3, etc.
klecmi
x1 is a member of class / category x2 (mass / plurality), within supergroup x3, with defining quality x4
leicmi
x1 is a member of class / category x2 (mass / plurality), within supergroup x3, with defining quality x4
nuncmibi'o
n1 is the integration of b1=c1 as a member/element of group/set c2 under conditions b3
selcmi
x1 is the set whose members are x2; x2 are the members of x1.
terporcmi
x1 is a member of the unordered set x2 upon which rules x3 are applied in order to produce list x4; x1 is a member of the elements constituting list x4.
cletu
x1 is a mathematical set, containing members x2
cei'u (exp!)
extracts an element from a set, category, class, group, collection, organization, system, etc.
fi'ai (exp!)
marks end of prenex in stack-based dialect
ji'oi (exp!)
This cmavo precedes a predicate (at least binary) and turns it into a conjunction, which syntactically behaves like JA cmavo. The predicate indicates the relationship between the two connected propositions. Terminator: {te'u}.
mei'e (exp!)
Accepts any number of sumti and turns them into a selbri-unit that means "x1 is among the referents of these sumti".
se'u'o (exp!)
selbri conversion question
aigne
x1 is an eigenvalue (or zero) of linear transformation/square matrix x2, associated with/'owning' all vectors in generalized eigenspace x3 (implies neither nondegeneracy nor degeneracy; default includes the zero vector) with 'eigenspace-generalization' power/exponent x4 (typically and probably by cultural default will be 1), with algebraic multiplicity (of eigenvalue) x5
porkifa'u
x1 is a sequence of sequences, whose elements are related respectively by x2 (property, arity is length of x1)
setmima
x1 is a mathematical set, containing members x2