Prove:
(Proposition (conv of sum): l+) ,
under the assumptions:
(Definition (conv): l2:) ,
(Definition (sum of functions): ⊕:) ,
(Definition (product of functions): ⊕:) ,
(Proposition (distance of sum): |++|) ,
(Proposition (distance of product): |**|) ,
(Proposition (max): max:) ,
(Proposition (min): min:) .
For proving (), we replace the variables by arbitrary constants (, ) and we prove:
(1) .
For proving (), we assume:
(3) ,
(4) ,
and we prove:
(2) .
Using the definition (), we expand the goal () and the assumptions () and () into:
(5)
(6)
(7)
By the assumptions () and (), we can take appropriate constants (, ) such that:
(9)
(10)
For proving (), we have to find appropriate values such that:
(8) .
For proving (), we replace the universal variables by arbitrary constants (), we assume:
(11) ,
and we prove:
(12) .
For using the assumptions () and () we have to find appropriate values , , and we assume:
(13)
(14)
We prove first:
(15) .
For proving (), by (), it suffices to prove
(18) .
Using the substitution from step (), the goal () becomes:
(36) .
Pending proof of ().
Now we assume () and we continue with the proof of ().
From (), by the assumptions () and () we obtain:
(16)
(17)
By the assumptions () and (), we can take appropriate constants (, ) such that:
(20)
(21)
For proving (), we have to find appropriate values such that:
(19) .
For proving (), we replace the universal variables by arbitrary constants (), we assume:
(22) ,
and we prove:
(23) .
For using the assumptions () and () we have to find appropriate values , , and we assume:
(24)
(25)
We prove first:
(26) .
For proving (), by (), it suffices to prove
(29) .
Formula () is proved because it becomes an instance of () by taking: .
Now we assume () and we continue with the proof of ().
From (), by the assumptions () and () we obtain:
(27)
(28)
For proving (), by (), it suffices to prove
(30) .
Using the substitution from step (), the goal () becomes:
(32) .
Using (), the goal () is transformed into:
(35) .
Formula () is proved because it becomes an instance of () by taking: .