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Comment by tptacek

2 years ago

I'm stuck on trying to work out what it would mean to de-lattice something. Would that transform a lattice basis into a standard vector space basis in R or something, or, like MOV, would it send the whole lattice to an element of some prime extension field?

In my mind's eye, it's cooler: it's like, you render the ciphertext as a raster image, and then "de-lattice" it to reveal the underlying plaintext, scanline by scanline.

i'm still working on understanding lattices better

but i can imagine, based on my own ignorance, creativity, and lack of correct understanding, would be some kind of factorization.

as I think while trying to better know what's a lattice, I imagine a lattice like a coordinate pair, but instead of each coordinate existing on a line, they exist on a binary tree (or some other directed graph explored from a root outwards without cycles)

which means you have two such binary-trees (not necessarily binary, but it's just easier to work with them seemingly)

and then you combine these into ONE lattice. so then, to de-lattice means to recover the binary trees.

but when I say binary tree I'm thinking about rational numbers (because stern broccott trees)

  • A lattice is like a vector space, but with exclusively integer coefficients. It's not a coordinate pair. If you think of vectors as coordinate pairs, a vector space is a (possibly unbounded) set of coordinate pairs. If you haven't done any linear algebra, a decent intuition would be mathematical objects like "the even numbers" or "the odd numbers", but substituting vectors (fixed-sized tuples of numbers) for scalars.