What is a challenge?

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Important points:
indivudual/family -> extensional/intensional

extensional: makes sense to have more than one.
Don't know which one you get and too time sonsuming to solve them all.

Issue of forced buying / reoffering
connection to extensional / intensional

Claim:
Extensional/reoffer does not make sense.

assume only one (extensional)
unique solution ?? Ask Bryan

reusing challenges is good in the intensional case.
In the extensional case: when solution is known,
no longer an interesting challenge
not clear for CSP classic: when problem (raw material) is known
and best assignment for it: challenge is gone unless raw material
is not the worst case.

Ahmed:
motivation for factor f.
The offerer of a challenge has the advantage of hiding a secret.
Therefore, the acceptor does not have to do as well as the offerer.

Bryan:
Need to demonstrate that you can solve the problem.
Clear for relative/intensional.
Requires that secret solution is revealed for specific instance.

For absolute/intensional also want to force release of solution?
For CSP: after raw material delivered, must deliver
an assignment covering price.

For absolute/extensional also want to force release of solution?
Basically makes a challenge usable only once.
Requires more work for producer of challenge: they must be ready
to solve it too if challenge is accepted.

Other point:
lower limit on buys
lower limit on reoffer
currently:
lower limit on buys: 0
lower limit on reoffer: all

other:
lower limit on buys: 1
lower limit on reoffer: 0
have to buy at least one: no need to reoffer

other:
lower limit on buys: 0
lower limit on reoffer: 25 %
  only at least 25% must be reoffered if nothing is bought
===

individual or family

relative or absolute

The renaissance challenges were:
individual/absolute/no quality 

individual:
solve f(x)=c 
is there a solution?
Give solution.
Prove that there is no solution.

Requirements for winning:

Problem TT
Family T: subset of TT
problem t in TT

family:
I will give you a problem of type T
and I will give you the quality of my solution and
you need to find a solution of relative
quality q.

I will give you a problem of type T
you need to find a solution of absolute
quality q.

individual:
relative:
Here is the problem with the quality of my solution.
You need to find a solution of relative
quality q.

individual:
absolute:
Here is the problem.
You need to find a solution of absolute
quality q.