I uploaded a photo with an excercise... What means the d(8,15) ?

I already know how the K Maps works, but I dont how to work K Maps with the '+(8,15)'



Thanks.

Moderators note: shown image in post

 

I've never seen this notation, so I'm guessing here; but I'm pretty sure I'm right. The d() means "don't care".

So your logic MUST make terms (0,1,3,5,14) HI, it MUST make terms (2,4,6,7,9,10,11,12,13) LO, and it doesn't matter what terms (8, 15) turn out to be.

 

This extract from following handout shows a similar notation, but differentiating maxterms from minterms.
https://courses.cs.washington.edu/courses/cse370/10wi/pdfs/lectures/04-CanonicalForms.pdf