Each Reinin dichotomy has a formula, an invariant, for its polarities. For instance, all extraverts have extraverted Information Elements in bold Fuctions; or All Sensing types have Se and Si in strong Fns etc...
Same applies for ITRs, here is the list of ITR dichiotomies formulae, organized by dichotomies generations.
1gen
extra intro
(1,3,6,8) in (1,3,6,8)
or
(1,3,6,8) in (2,4,5,7)
2gen
irr/ra
(1,3,5,7) in (1,3,5,7)
or
(1,3,5,7) in (2,4,6,8)
st/dn
(1,2,3,4) in (1,2,3,4)
or
(1,2,3,4) in (5,6,7,8)
3gen
carefree/farsighted
(1,5) in (1,4,5,8)
or
(1,5) in (2,3,6,7)
yielding/obstinate
(2,6) in (2,3,6,7)
or
(2,6) in (1,4,5,8)
logic/ethic
(2,8) in (1,2,7,8)
or
(2,8) in (3,4,5,6)
intuitive/sensory
(1,7) in (1278)
or
(17) in (3456)
merry/serious
(26) in (1256)
or
(26) in (3478)
judicious/decisive
(15) in (1256)
or
(15) in (3478)
constructivist/emotivist
(28) in (2358)
or
(28) in (1467)
tactical strategic
(17) in (1467)
or
(17) in (2358)
4gen
superlocal are more complex here i guess xD