E-commerce products filter

E-commerce products filter

Im trying to biuld a filter algorithm for my product list.
For example I have 2 Televisions.
First one is: screen Size 117 Cm, brand Samsung. Second one is: screen
size 203 CM, brand Sharp.
And i have the following filters:
Brand: Samsung, Sharp
Screen size: 117 Cm, 203 CM
If I want to see only Samsung TVs and I check the Samsung Filter, how can
I reach to conclusion that I should remove Screen size 203 from filters,
because samsung have only 117 cm tv.
But if i check sharp tv and samsung in the same time, then I should see
both screen size filters.
I m asking for an idea for some php/mysql algorithm.
I hope you understand what i m asking.
For an example look here:
http://www.ebay.co.uk/sch/Televisions-/11071/i.html?_dcat=11071&Display%2520Technology=LED%2520LCD&rt=nc
The website knows how many products they have before user checks any
filter: eg: "40" - 49" (326)) -> they know that they have 326 products
before user checks that filter.
Thanks