 Sure, here's an example of a DECLARE model for a hypothetical Purchase-to-Pay process:
```python
DECLARE_model = {
    'existence': {'Purchase Order': {'support': 1.0, 'confidence': 1.0}},
    'absence': {'Invoice Received': {'support': 1.0, 'confidence': 1.0}},
    'exactly_one': {'Payment': {'support': 1.0, 'confidence': 1.0}},
    'init': {'Purchase Order': {'support': 1.0, 'confidence': 1.0}},
    'responded_existence': {'Purchase Order': {'Goods Receipt': {'support': 1.0, 'confidence': 1.0}}},
    'coexistence': {'Delivery Note': {'Invoice Received': {'support': 1.0, 'confidence': 1.0}}},
    'response': {'Goods Receipt': {'Invoice Received': {'support': 1.0, 'confidence': 1.0}}},
    'precedence': {'Purchase Order': {'Goods Receipt': {'support': 1.0, 'confidence': 1.0}}},
    'succession': {'Purchase Order': {'Payment': {'support': 1.0, 'confidence': 1.0}}},
    'altresponse': {'Purchase Order': {'Invoice Received': {'support': 1.0, 'confidence': 1.0}}},
    'chainresponse': {'Purchase Order': {'Goods Receipt': {'Invoice Received': {'support': 1.0, 'confidence': 1.0}}}},
    'noncoexistence': {'Payment': {'Goods Receipt': {'support': 1.0, 'confidence': 1.0}}},
    'nonsuccession': {'Goods Receipt': {'Payment': {'support': 1.0, 'confidence': 1.0}}}}
```
Explanation of the constraints:

* Existence: A Purchase Order is created at least once in the process.
*