Купил немного btc всё прошло отлично!)

у меня находит.

Hi,

I was reading the paper written by Kuramesan and Bentov with title "How to use Bitcoin to Design Fair Protocols".
Source: https://eprint.iacr.org/2014/129.pdf
Specifically, the sender creates a transaction which can be redeemed the following way:
1) By providing the Sender's signature AND the Receiver's signature
2) By Receiver's signature and a witness/proof which will make a circuit/function valid

Whichever of the conditions comes claims the transaction. My problem in understanding is what this circuit/function should be. Can it a random secret chosen by so if we pass through a hash function that is the circuit it can easily be verified since the receiver has to reveal this secret through it's claim transaction?
Is my assumption correct?

Furthermore, about the fair reconstruction protocol, it says in page 10 of the paper, a Sender may use tags to specify a Fcr transaction with the guarantee that its deposit can be claimed by a receiver if only he provides the corresponding token. As I guess this in the fair reconstruction protocol, is represented through the circuit functionality, but when the authors design the naive approach they declare Ti as Token(ai) where a I guess it is a secret since on the footnote they declare that it should contin some randomness. Any thoughts on this?

I would like to understand more how the network, specially a node decides about which transactions will relay and which blocks and how it does achieve that. Is there something more than the wiki I can read?

Also I have not understood. Messages are the first thing a client does when connection to the network and after it has the info it needs it starts relaying? Also is it possible for a node not to relay blocks and transactions?