interactTopExp :: [Xi] -> Xi -> [Pair Type]
interactTopExp [s,t] r
  | Just 0 <- mbZ = [ s === num 0 ]                                       -- (s ^ t ~ 0) => (s ~ 0)
  | Just x <- mbX, Just z <- mbZ, Just y <- logExact  z x = [t === num y] -- (2 ^ t ~ 8) => (t ~ 3)
  | Just y <- mbY, Just z <- mbZ, Just x <- rootExact z y = [s === num x] -- (s ^ 2 ~ 9) => (s ~ 3)
  where
  mbX = isNumLitTy s
  mbY = isNumLitTy t
  mbZ = isNumLitTy r
interactTopExp :: [Xi] -> Xi -> [Pair Type]
interactTopExp [s,t] r
  | Just 0 <- mbZ = [ s === num 0 ]                                       -- (s ^ t ~ 0) => (s ~ 0)
  | Just x <- mbX, Just z <- mbZ, Just y <- logExact  z x = [t === num y] -- (2 ^ t ~ 8) => (t ~ 3)
  | Just y <- mbY, Just z <- mbZ, Just x <- rootExact z y = [s === num x] -- (s ^ 2 ~ 9) => (s ~ 3)
  where
  mbX = isNumLitTy s
  mbY = isNumLitTy t
  mbZ = isNumLitTy r
interactTopExp [s,t] r
  | Just 0 <- mbZ = [ s === num 0 ]                                       -- (s ^ t ~ 0) => (s ~ 0)
  | Just x <- mbX, Just z <- mbZ, Just y <- logExact  z x = [t === num y] -- (2 ^ t ~ 8) => (t ~ 3)
  | Just y <- mbY, Just z <- mbZ, Just x <- rootExact z y = [s === num x] -- (s ^ 2 ~ 9) => (s ~ 3)
  where
  mbX = isNumLitTy s
  mbY = isNumLitTy t
  mbZ = isNumLitTy r