# Slot: system_size 


_System size (van Kampen Ω) for the stochastic 'gillespie' backend: the number of discrete units per unit of the activity variable, and the sole source of noise. Runs a mean-field rate model as a finite birth-death process (Gillespie SSA): the activity state variable X becomes a discrete count n ≈ Ω·X, its relaxation equation tau*X' = -X + F(...) is read as birth propensity Ω·F/tau (the gain) and death propensity n/tau (the leak), while the remaining state variables integrate deterministically between events. Larger Ω means finer discreteness and weaker fluctuations, recovering the deterministic mean field as Ω→∞. For an activity already expressed as a fraction in [0,1], Ω is the population size N; for a firing rate it is N divided by the rate at full activation. Required by the 'gillespie' backend; ignored by every other backend._



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URI: [tvbo:slot/system_size](https://w3id.org/tvbo/slot/system_size)
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## Applicable Classes

| Name | Description | Modifies Slot |
| --- | --- | --- |
| [ExecutionConfig](../classes/ExecutionConfig.qmd) | Configuration for computational execution (parallelization, precision, hardwa... |  no  |






## Properties

### Type and Range

| Property | Value |
| --- | --- |
| Range | [xsd:float](http://www.w3.org/2001/XMLSchema#float) |
| Domain Of | [ExecutionConfig](../classes/ExecutionConfig.qmd) |

### Cardinality and Requirements

| Property | Value |
| --- | --- |
### Slot Characteristics

| Property | Value |
| --- | --- |
| Owner | [ExecutionConfig](../classes/ExecutionConfig.qmd) |












## Identifier and Mapping Information





### Schema Source


* from schema: https://w3id.org/tvbo




## Mappings

| Mapping Type | Mapped Value |
| ---  | ---  |
| self | tvbo:system_size |
| native | tvbo:system_size |




## LinkML Source

<details>
```yaml
name: system_size
description: 'System size (van Kampen Ω) for the stochastic ''gillespie'' backend:
  the number of discrete units per unit of the activity variable, and the sole source
  of noise. Runs a mean-field rate model as a finite birth-death process (Gillespie
  SSA): the activity state variable X becomes a discrete count n ≈ Ω·X, its relaxation
  equation tau*X'' = -X + F(...) is read as birth propensity Ω·F/tau (the gain) and
  death propensity n/tau (the leak), while the remaining state variables integrate
  deterministically between events. Larger Ω means finer discreteness and weaker fluctuations,
  recovering the deterministic mean field as Ω→∞. For an activity already expressed
  as a fraction in [0,1], Ω is the population size N; for a firing rate it is N divided
  by the rate at full activation. Required by the ''gillespie'' backend; ignored by
  every other backend.'
from_schema: https://w3id.org/tvbo
rank: 1000
owner: ExecutionConfig
domain_of:
- ExecutionConfig
range: float

```
</details></div>