Bitcoin Cash difficulty before first hard fork: Emergency Difficulty Adjustment (EDA) What were the network rules regarding the difficulty adjustments of the Bitcoin Cash chain, before the first hard fork was implemented on November 13th, 2017?
There was a rule that was a function of the time taken to find the last 2016 blocks, and one based on the Median Time of the last 11 blocks. What was the effect of these rules?
The first rule is well understood.
The second rule, ensures that difficulty gets readjusted quicker if the MTP between blocks is big (12h.)   

In practice:
Check the MTP of the current block (mining time of a block 6 blocks earlier)
compare to the MTP time of a block mind 6 blocks earlier
if the difference is 12 hours then difficulty will reset
for example:
block 478574 has an MTP of Aug 1 14:39: UTC
block 478568 has an MTP of Aug 1  11:52 UTC
so not yet 12 hours apart   

also see: https://medium.com/@jimmysong/bitcoin-cash-difficulty-adjustments-2ec589099a8e (edit: fixed link)