1 files changed, 1 insertions, 1 deletions
diff --git a/doc/couple.md b/doc/couple.md
index 3b11b2b3..3cc1ac8f 100644
--- a/doc/couple.md
+++ b/doc/couple.md
@@ -49,6 +49,6 @@ The pair function, which creates a list from its arguments, can be written `Pair
 
 ## Definitions
 
-As discussed above, `≍` is equivalent to `>{⟨𝕩⟩;⟨𝕨,𝕩⟩}`. To complete the picture we should describe Merge fully. Merge is defined on an array argument `𝕩` such that there's some shape `s` satisfying `∧´⥊(s≡≢)¨𝕩`. If `𝕩` is empty then any shape satisfies this expression; `s` should be chosen based on known type information for `𝕩` or otherwise assumed to be `⟨⟩`. If `s` is empty then `𝕩` is allowed to contain non-arrays as well as array scalars, and these will be implicitly promoted to arrays by the `⊑` indexing used later. We construct the result by combining the outer and inner axes of the argument with Table; since the outer axes come first they must correspond to the left argument and the inner axes must correspond to the right argument. `𝕩` is a natural choice of left argument, and because no concrete array can be used, the right argument will be `↕s`, the array of indices into any element of `𝕩`. To get the appropriate element corresponding to a particular choice of index and element of `𝕩` we should select using that index. The result of Merge is `𝕩⊑˜⌜↕s`.
+As discussed above, `≍` is equivalent to `>{⟨𝕩⟩;⟨𝕨,𝕩⟩}`. To complete the picture we should describe Merge fully. Merge is defined on an array argument `𝕩` such that there's some shape `s` satisfying `∧´⥊(s≡≢)¨𝕩`. If `𝕩` is empty then any shape satisfies this expression; `s` should be chosen based on known type information for `𝕩` or otherwise assumed to be `⟨⟩`. If `s` is empty then `𝕩` is allowed to contain atoms as well as array scalars, and these will be implicitly promoted to arrays by the `⊑` indexing used later. We construct the result by combining the outer and inner axes of the argument with Table; since the outer axes come first they must correspond to the left argument and the inner axes must correspond to the right argument. `𝕩` is a natural choice of left argument, and because no concrete array can be used, the right argument will be `↕s`, the array of indices into any element of `𝕩`. To get the appropriate element corresponding to a particular choice of index and element of `𝕩` we should select using that index. The result of Merge is `𝕩⊑˜⌜↕s`.
 
 Given this definition we can also describe Rank (`⎉`) in terms of Each (`¨`) and the simpler monadic function Enclose-Rank `<⎉k`. We assume effective ranks `j` for `𝕨` (if present) and `k` for `𝕩` have been computed. Then the correspondence is `𝕨F⎉k𝕩 ←→ >(<⎉j𝕨)F¨(<⎉k𝕩)`.