x1 is a logical 'NOT' statement resulting from the (multiplicative) negation of/applying the 'NOT' operator to x2 (du'u); x1 is the logical negation/negative of x2.
x1 is a material conditional/'IF' statement (logical statement) saying that x2 (du'u) logically implies x3 (du'u) ("x3 is true if x2 is true; if x2, then x3; x2 being true is sufficient to guarantee the truth of x3").
x1 is a logical statement of proposition-equivalence/is a biconditional/'IFF' statement saying that x2 (du'u) is true if and only if x3 is true ("x2 is logically equivalent to x3; x2 being true is sufficient and necessary for guaranteeing the truth of x3; x2 iff x3").
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}.
Property relativizing determiner / unary quantifier constructor. {kai'i} introduces a predicate whose first argument slot becomes filled by the property made by taking the bridi in which this {kai'i} appears and putting {ce'u} into the argument slot in which this {kai'i} argument was located. Put formally, "kai'i brodi cu brodu" = "lo ka ce'u brodu cu brodi". Additionally, a {kai'i} term has a rightward logical scope, like quantifiers and adverbials.