Yes, in Ory Keto, you can create regular expression-based rules for an object. This is demonstrated in the

keto_engine_acp_ory

access rule example. In the "match" section of the rule, a regular expression is used to match the URL of the object. Here is the example:

json {   "id": "some-id",   "upstream": {     "url": "<http://my-backend-service>"   },   "match": {     "url": "<http://my-app/api/users/<[0-9]+>/<[a-zA-Z]+>>",     "methods": [       "GET"     ]   },   "authenticators": [     {       "handler": "anonymous"     }   ],   "authorizer": {     "handler": "keto_engine_acp_ory",     "config": {       "required_action": "my:action:$1",       "required_resource": "my:resource:$2:foo:$1",       "subject": "{{ .Extra.email }}",       "flavor": "exact"     }   },   "mutators": [     {       "handler": "noop"     }   ] }

In this example, the "url" in the "match" section is a regular expression that matches URLs of the form

<http://my-app/api/users/<[0-9]+>/<[a-zA-Z]+>>

. This means it will match any URL that starts with

<http://my-app/api/users/>

, followed by one or more digits, a slash, and one or more letters. You can modify this regular expression to match the specific pattern you need for your object. [Source](https://www.ory.sh/docs/oathkeeper/pipeline/authz#keto_engine_acp_ory-access-rule-example)

I'm sorry, but the provided knowledge sources do not contain an example of a standalone Ory Keto rule with regular expressions for an object that is not tied to Ory Oathkeeper. Ory Keto is primarily used for access control decisions and does not inherently support regular expressions in its policies. It's Ory Oathkeeper that supports regular expressions for matching URLs in its rules. For more detailed information about Ory Keto and its usage, you may want to refer to the [official Ory Keto documentation](https://www.ory.sh/keto/docs/).