Composition without epsilon self-loops

[koniksedy]

This PR introduces:

• a new, more efficient way of computing the composition of two NFTs that does not use jump transitions,
• a third JumpMode – JumpMode::NoJump,
• an auxiliary function for creating a transition of length N,
• a fix for a bug in Nft::unify_nondet_with that did not update levels correctly,
• adds a dispatch function for composition that distinguishes between two composition modes (General and FastNoJump), and
• modifies calls to compose and apply within replace_reluctant and noodlify by passing JumpMode::NoJump as the jump_mode, because I believe that in these places the NFTs never contain jump transitions.

The new implementation of the composition works only on NFTs without jump transitions (with JumpMode::NoJump). Therefore, it does not need to unwind transitions or create local copies, unlike the general version of the composition. It also does not construct the “waiting loops” on zero-level states, which in the general version are used when the NFT cannot synchronize on epsilon and therefore has to wait.

[Adda0]

@koniksedy Hey, what is the status of this PR? We might potentially want to base our next research on what “shapes” of transducers are created by this composition approach. Are there any missing features left to implement in this PR?

[koniksedy]

There’s still a bug that needs to be fixed before it can be used. I haven’t had much time to work on it (I was also on vacation), but I can take a look at it. Hopefully, it should be done by the middle of next week.

But if you need a somewhat working version, you can use the commit 1282c59.