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  • 0 posts edited
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Dec
29
answered Skolemization of a Formula
Dec
29
comment Why is 'abuse of notation' tolerated?
Without further research you are saying that I were using non-standard notation. May I show you the following reference: ISO 31-11: ⇒ p ⇒ q implication sign if p then q; p implies q Can also be written as q ⇐ p. Sometimes → is used. en.wikipedia.org/wiki/ISO_31-11 . Seems you are suffering from some severe self overestimates, the only thing that is distracting here.
Dec
29
revised Skolemization of a Formula
edited tags
Dec
29
revised Skolemization of a Formula
deleted 99 characters in body
Dec
29
revised Skolemization of a Formula
added 98 characters in body
Dec
29
asked Skolemization of a Formula
Dec
29
revised Is the validity of the Skolemization of a sentence A infers the validity of A?
edited body
Dec
29
answered Is the validity of the Skolemization of a sentence A infers the validity of A?
Sep
25
comment What are the historical roots of cryptarithmetic?
This is a hukumenzan: janko.at/Raetsel/Nikoli/Hukumenzan.htm . Somebody told me the translation is "prune and peach are friends", and the script is Hiragana.
Sep
23
comment What are the historical roots of cryptarithmetic?
Looks they are called nowadays hukumenzan in Japan. But how about China? I still don't know.
Sep
23
comment Induction, how often?
I have constructed the example from the property that ∀x doesn't preserve countable infinite ascending unions. The existential quantifier does so. But I am not yet sure what the implications are for induction. Maybe one can construct a predicate q, prove it by a single induction, and then derive p. Like following the odd numbers and hypothetically following the even numbers at the same time, and joining the two together resolving the hypothesis. The hypothesis would be p(1).
Sep
23
revised Induction, how often?
added 43 characters in body
Sep
23
comment Induction, how often?
Greetings from CH to CH. Looks like an agreement that ∀x p(x) holds. But somehow the proof doesn't go through with a single induction over p, does it?
Sep
23
revised Induction, how often?
deleted 1 characters in body
Sep
23
asked Induction, how often?
Sep
22
comment Why does the expression of Peano induction has to be second order?
Actually first order induction means that one adds a schema. So the X is really quantified, but not in the object logic but syntactically on the meta-level.
Sep
21
revised What are the historical roots of cryptarithmetic?
added 58 characters in body
Sep
21
answered How to prove AB is not equal to BC
Sep
21
asked What are the historical roots of cryptarithmetic?
Aug
25
revised What kind of logics satisfy the coincidence lemma?
added 286 characters in body; edited title