Sure, let's go through each concept in Petri nets and suggest an opposite as well as a more general concept:

1. **Source Place**
    - **Opposite Concept: Sink Place**
    A source place is a place in a Petri net with no incoming edges, only outgoing ones. It represents the starting point for tokens (resources, data, etc.). The opposite would be a sink place, which has no outgoing edges, only incoming ones, indicating it's a point where tokens leave the system or accumulate.
    - **More General Concept: Place**
    The more general concept would be a "place" in a Petri net, which can be a source, sink, or an intermediate place with both incoming and outgoing edges. It represents any condition or state in the system being modeled by the Petri net.

2. **Immediate Transition**
    - **Opposite Concept: Timed Transition**
    Immediate transitions are events that occur instantaneously as soon as their preconditions (input places are populated with sufficient tokens) are satisfied. The opposite is a timed transition which incorporates a delay or time element for firing, representing processes that consume time.
    - **More General Concept: Transition**
    The more general concept is a "transition" in a Petri net, which may be immediate or timed (stochastic, deterministic, or with assigned duration). It represents events that can cause the movement of tokens from input places to output places.

3. **Live Transition**
    - **Opposite Concept: Dead Transition**
    A live transition is one that can be fired at least once in every reachable marking of the Petri net, implying that it will never become permanently disabled. The opposite, a dead transition, is one that can reach a state where it can never be fired again. This indicates a lack of progress or potential deadlock within the system.
    - **More General Concept: Transition Properties**
    A more general concept would encompass all properties of transitions. These might include liveness, boundedness, safeness, etc., covering all the potential characteristics that describe how transitions behave in a Petri net.

4. **Bounded Net**
    - **Opposite Concept: Unbounded Net**
    A bounded net is a Petri net where every place has a maximum number of tokens that it can hold, which will never be exceeded regardless of how transitions fire. This implies predictable and controlled resource usage. The opposite is an unbounded net, where the number of tokens in some places can grow indefinitely, leading to potential issues with uncontrolled growth or modeling infinite capacities.
    - **More General Concept: Net Properties**
    A general concept would be the "properties of a Petri net," referring to various features such as boundedness, safeness, liveness, fairness, etc. It considers the characteristics and behaviors that a Petri net can exhibit, without limiting the scope to any specific aspect.

5. **Free Choice Net**
    - **Opposite Concept: Non-Free Choice (or Restricted Choice) Net**
    A free choice net is a class of Petri net where the choices offered by transitions are not influenced by the state of other places that are not in direct connection to those transitions. Every choice is "free" in the sense that the firing of a transition is not dependent on the state of other places. The opposite would be a non-free choice net, where the decisions (transition firings) are dependent on the states of other places, leading to more complex behavior and restrictions.
    - **More General Concept: Petri Net Classes**
    The broader concept would involve other "classes of Petri nets," such as state machine nets, marked graphs, workflow nets, and so forth. This includes a complete taxonomy of Petri nets, with their unique properties and constraints, providing a richer framework for modeling complex systems.