Here are some opposite and more general concepts related to the Petri net concepts you provided:

**Concept** | **Opposite Concept** | **More General Concept**
------- | -------- | --------
Source Place | **Sink Place**  | **Place**
Immediate Transition | **Delayed Transition** | **Transition**
Live Transition | **Dead Transition** | **Behavioral Element**
Bounded Net | **Unbounded Net** | **Net System**
Free Choice Net | **Non-Free Choice Net** | **Petri Net Structure**

**Explanations:**

* **Source Place vs. Sink Place:** A source place is a place with no incoming arcs, essentially the starting point of tokens in a net. A sink place has no outgoing arcs, representing the end point for tokens. Both are specific types of places within a Petri net.

* **Immediate Transition vs. Delayed Transition:** An immediate transition fires as soon as it is enabled (has sufficient input tokens), without consuming any time. A delayed transition requires some time to fire, potentially modeling real-world delays.

* **Live Transition vs. Dead Transition:** A live transition can be enabled infinitely often during the net's execution. A dead transition can never be enabled, becoming inactive and irrelevant.

* **Bounded Net vs. Unbounded Net:** A bounded net has a finite number of tokens in each place at any given time. An unbounded net allows places to potentially hold an infinite number of tokens, which can lead to complex behavior.

* **Free Choice Net vs. Non-Free Choice Net:** In a free choice net, for any given marking and enabled transition, there is always a choice of input places that can be used to fire the transition. Non-free choice nets may restrict this choice, leading to more deterministic behavior.


Let me know if you have any more Petri net concepts you'd like to explore!