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Feb
1
revised A correct proof for this pumping lemma example?
added 6 characters in body
Feb
1
answered Compute number of points having same property
Feb
1
answered A correct proof for this pumping lemma example?
Feb
1
comment Compute number of points having same property
I see, the question does not correspond to your question at all. The points in a certain region are flipped, so you do not know the number of green points, you have to regard the parity of flips.
Feb
1
comment Compute number of points having same property
The word 'green' has not been found in the linked pdf.
Feb
1
comment Compute number of points having same property
What kind of question do you want to ask for the 2d grid? The envelopping cuboid in your question is also redundant. This is very, very unlikely for a contest problem to contain so much redundant information. Where is it from?
Feb
1
comment Compute number of points having same property
If there are $a$ green points in each $x$-segment, then there are $a \cdot (y_2-y_1) \cdot (z_2-z_1)$ green points in total in the small cuboid. We do not need $b$ and $c$ here. So, possibly you want to express things only with $a,b,c$, but there is clearly a restriction missing on the actual question.
Feb
1
comment Coin flipping probability game ; 7 flips vs 8 flips
@PatrickT If one of the two players has an advantage after the first seven tosses, the extra toss cannot take the victory from them (if the extra tosser is in the lead, the extra toss can only help, if the other one is in the lead, the extra toss can only make it a tie which is a win for the other one anyway). This is the reason you can "discard" them. In the remaining case, the 8th toss IS the tiebreaker. There is nothing sleight of hand about it.
Feb
1
comment Compute number of points having same property
Your information is unclear. Do you want to say that between (x1, y, z) and (x2,y,z), there are always exactly $a$ green points? And is a cuboid a rectangular parallelepiped? In that case, the infomation would be highly redundant, so please check your source.
Feb
1
comment Listening to music while studying math?
I can believe that music is distracting when I am trying to memorise things, but I doubt it when I try to understand something. I actually like to sing or hum myself while thinking about mathematics.
Jan
28
comment How find this sum $\sum_{k=1}^{n}\frac{(a_{k}+1)(b_{k}+1)}{a_{k}+b_{k}+3}$
Why do you expect a nice result?
Jan
28
comment Prove that if $k^2=o(n)$, then $n(n-1)(n-2)…(n-k+1) \approx n^k$
What is the leading term on the left? What is the second term? This should explain the relevance of your condition-
Jan
28
awarded  Good Answer
Jan
27
awarded  Nice Answer
Jan
27
answered Is the Look and Say Sequence a “proper” maths problem?
Jan
27
comment What is the minimal number of weighings required to find an odd (lighter) coin out of 80?
@AndréNicolas Sorry, I did not see the previous version of the question.
Jan
27
comment What is the minimal number of weighings required to find an odd (lighter) coin out of 80?
@Androiddeveloper "Meaning" is a very vague word. You should be more specific what you want to know about this question, and what you would regard as an answer. What is the meaning of the question: "If I gave you and apple, we would have the same amount of apples. If you gave me an apple, I would have twice your amount of apples. How many apples do we have?"? Your question can be viewed as an example for ternary digits, information theory or something else. There is no "the meaning".
Jan
27
comment What is the minimal number of weighings required to find an odd (lighter) coin out of 80?
@AndréNicolas I do not get your comment. Why should anyone think that it is $5$?
Jan
27
comment What is the minimal number of weighings required to find an odd (lighter) coin out of 80?
"what is the meaning of this question" Can you explain what you want?
Jan
24
reviewed Leave Open Axiom of Completeness for set of integers