@Tammy481
It is not possible. What you want is a discount based on check-in day (Tuesday, wednessday) and a certain lenght of stay. That is a "if x then y" situation and the platform does not provide programmable features.
Offcourse you can manually set a lower price in the calender on Tuesday and wednessday, but it does affect every reservation, also the ones you do not want to discount.
Alternative (Smart Pricing must be turned off):
If you only want maximum 4 nights stays and a minimum stay of ?) on bookings starting on Tuesday and wednessday , they create a ruleset which limits the lenght of stay. and applies a discount for 2,3 and 4 nights. Then apply the ruleset to every tuesday/wednessday you want it to be effective.