# Search results

1. ### Three-phase transformer DC-resistances

aaah stupid me, that's right, the triangle confused me :D I calculated (80*80 / 80+80) + 80 and got the right answer! thanks very very much
2. ### Three-phase transformer DC-resistances

isnt the total resistance of the triangle that 80 ohms? so resistance of one winding should then be 80/3? well apparently not because i dont get the right answer with that
3. ### Three-phase transformer DC-resistances

Homework Statement Three-phase transformer, 20/0.5 kV, dyn11. Not connected to the grid. DC-resistance between two primary windings is measured to be 80 ohm. What is the DC-resistance of ONE primary coil Homework Equations The Attempt at a Solution I thought I could just...
4. ### Injection and surjection

Homework Statement Are the given functions injective? Surjective? a) seq: N -> Lists[N] b) f: Lists[A] -> P(A), f(x)=(<x1,x2,...,xn>)={x1,x2,...,xn} Homework Equations The Attempt at a Solution a) Ok so the domain contains a sequence of natural numbers. and the range contains a list...
5. ### Truth table and proving a tautology

so do you think that I have done it right and the excercise is badly worded?
6. ### Truth table and proving a tautology

yes, it is just like that in the excercise paper
7. ### Truth table and proving a tautology

Homework Statement I'm supposed to prove that this statement is a tautology (with truth table): (p -> ((p OR q) AND ~q)) = (~p OR ~q) AND p Homework Equations The Attempt at a Solution p | q | ~p | ~q | p OR q | (p OR q) AND ~q | p -> ((p OR q) AND ~q) | (~p OR ~q) | (~p OR...
8. ### Hasse diagram of a POSET

i still dont get it :( for example why is 2 immediate predecessor of 10
9. ### Hasse diagram of a POSET

Ok I dont understand one thing...We ahd this example in school We have poset < {1,2,5,7,10,14,35,70}, | > | meas factor, for example a|b means b=ka, where k=integer and we got this Hasse diagram 70 / | \ 10 14 35 | X X | 2 5 7 \ | / 1 X means...
10. ### Finding Equivalence Class

 must then be only {0} What about R: R <-> R, where xRy, iff floor(x) = floor(y) i dont know if floor() is the right way to write floor function, but cant find the correct symbol.  is then something like {2, 2.1, 2.2, ... , 2.99999...} but what is the correct way to write it? Because 2...
11. ### Finding Equivalence Class

I thought I understood the b) part, but now im not sure if i do deeply enough. So, in each class the elements are "equivalent" in the way the equivalence relation is defined? xmod4 = ymod4 means every element which has same modulus when divided by 4 belong to same class? can [-3] then be only...
12. ### Finding Equivalence Class

if x = -3, then y can then be 3 or -3 What is [-3]? I dont know, {..., ???, -3, ???, ...}
13. ### Finding Equivalence Class

hmmm...y must always be +x or -x? but i dont understand how the classes are formed. For example class , does it mean the list starts at 0? In the b-part the list increases always by 4, but what about in this, by 1?
14. ### Finding Equivalence Class

Homework Statement Find the equivalence class  for the following equivalence relations: a) R: Z <-> Z, where xRy, iff |x| = |y| b) T: N <-> N, where xTy, iff xmod4 = ymod4 N means natural numbers etc...there wasnt the correct symbols in the latex reference Homework Equations ?? The...