I am looking for a FOSS software that is similar in spirit to a tool called TheBrain. TheBrain can be described as a sophisticated mind mapping tool, where you can visualize concepts and establish relationships among them.
One major use case I am planning to use the requested software for would be historical research. Since in historical research you are dealing with many dates, the software should have a notion of time (which TheBrain unfortunately doesn't have). That is, the user should be able to associate concepts and relationships with timestamps.
The below list represents a prioritized feature set:
- FOSS (if necessary I must be able to modify the software according to my needs)
- Visualization of concepts and their relationships
- Ability to associate concepts and relationships with a timestamp or timespan (e.g. kill(Roman senators, Julias Caesar) on (44 BC, March, 15))
- Ability to attach documents such as websites or PDF documents to concepts
- Quick navigation through the knowledge base (e.g. search for concepts)
- Ability to collaboratively work on a shared knowledge base with multiple people
- Written in a language that will run on most platforms without adaptation (e.g. Java, Python)
I am aware that the above requirements are very high, but I am already grateful for recommendations that fulfill only 3 to 4 of the requirements.