Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Open problems in cross-chain protocols   Blockchain interoperability is a prominent research field which aims to build
bridges between otherwise isolated blockchains. With advances in cryptography,
novel protocols are published by academia and applied in different applications
and products in the industry. In theory, these innovative protocols provide
strong privacy and security guarantees by including formal proofs. However,
pure theoretical work often lacks the perspective of real world applications.
In this work, we describe a number of hardly researched problems which
developers encounter when building cross-chain products.

29
The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
17
The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th
4
The categories of this paper are: cond-mat
12
The categories of this paper are: nucl-th
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
25
The categories of this paper are: patt-sol
2
The categories of this paper are: math
23
The categories of this paper are: solv-int