MATCH_RECOGNIZE to find events that do not end with certain pattern

I have the transaction audit history as following. All audits start with a INIT and may have a REVERSAL and a MODIFICATION. I need to find all the audits with INIT -> REVERSAL but no MODIFICATION

I tried using the Regex End Anchor ($) as following, but it also returns the audits that end with MODIFICATION:

select 
 *
from audit_table
match_recognize(
    partition by transaction_id
    order by audit_ts
    ALL ROWS PER MATCH
    PATTERN (INIT REVERSAL$)
    DEFINE
          INIT as iff(ACTION='INIT',TRUE,FALSE),
          REVERSAL as iff(ACTION='REVERSAL',TRUE,FALSE),
          MODIFICATION as iff(ACTION='MODIFICATION',TRUE,FALSE)
);

Please advise.

The pattern needs to be altered using quantifiers ^INIT{1} REVERSAL{1}$:

select  *
from audit_table
match_recognize(
    partition by transaction_id
    order by audit_ts
    ALL ROWS PER MATCH
    PATTERN (^INIT{1} REVERSAL{1}$)
    DEFINE
         INIT as ACTION='INIT',
         REVERSAL as ACTION='REVERSAL',
         MODIFICATION as ACTION='MODIFICATION'
)
ORDER BY transaction_id, audit_ts;

Snowflake supports boolean data type natively so:

INIT as iff(ACTION='INIT',TRUE,FALSE),
<=>
INIT as ACTION='INIT',

Output: