If you read an LGPL projects source code and that inspires an entirely different implementation, is that work still a derived work?

I really want to use PGM for an application that I'm working on for one my companies. That application will never be distributed, it's for internal use only. There is an implementation called OpenPGM and a (I believe) derivative work javapgm that implements the protocol. Both are licensed under the LGPL.

My question is if I read the source code for these libraries and use that knowledge to help create an Erlang PGM implementation, would that be considered a derived work? I would prefer to release my implementation under the BSD license, so I'm not trying to take something for nothing, but I want to play fair.

In short then:

1. Would / should my version be released under the LGPL?
2. If my company is using it internally only, would there be any restrictions on how it could use that library? (it would never be distributed outside the company).
3. Is it in the spirit of the LGPL license to do what I want to do?

Thanks in advance! :)

I don't think it would be a derived work unless there is a 1:1 correlation between lines of code in your thing and the open source code. We're not talking about a patent here, where the concept of the invention is important.

1. If it is only used internally then it doesn't have to be.

2. You could never be certain that it doesn't accidentally leak out or get shared or included in another project.

3. You should try to work with OpenPGM to make the Erlang interface that you need; then it is open source, other people may help maintain it for you, you get a free code review