Alternate Ability groups

[CeeDub]

Salutations!

Suppose a character has two or more groups of abilities that are AAs of each other, but only within their own group. Say, frex, a psionic cyborg. The technological abilities would form one group, and the psionic abilities another. For the sake of argument, the character also has Compartmentalized Mind, so he could use one of each group every turn. Or Group 1 are attacks and Group 2 are movement abilities. Whatever.

Let's assume the (unmodified for AA) abilities cost CP like so:
Group 1:
Ability A [100]
Ability B [80]
Ability C [20]
Group 2:
Ability D [40]
Ability E [30]
Ability F [10]

Would you then buy only the two most expensive abilities of each group (A and D) and apply the AA modifier to the rest; or buy the two most expensive abilities (A and B), and treat the group thing as a special effect?

[Nereidalbel]

Buy A and D. They're different sets entirely, and subject to different countermeasures.

[PK]

Originally Posted by CeeDub

Would you then buy only the two most expensive abilities of each group (A and D) and apply the AA modifier to the rest

This.

For each group of AAs, you pay full price for the most expensive ability and then 1/5 cost for each additional ability. Since your two AA groups (ABC and DEF) aren't related in any way, you treat them completely separately.

Note that there are more complex rules for AAs detailed in GURPS Power-Ups 8: Limitations, in which you can do things like "I have six abilities and I can use any two of them at once." (Basically, you pay full price for the most expensive X abilities, where X is how many you can use at once.)