automata – how i can find actual proof about the (non-)regularity of this language?

Let us consider the alphabet Z=(a,b) and Langauge L= {(a^i+1)(b^2*i)|i e N ):

Apply the Pumping Lemma to prove, if possible, that this language is not regular. If possible, verify
the proof by assigning a suitable (numerical) value to the pumping length.

How I can prove this

Hxd editor find inside a file by entering some hex search values and without knowing other values [closed]

I have a file with some parts with this hex below that i want find with random numbers

hex = 31 00 39 00 39 00 20 00 38 00 33 00 30 00 20 00 35 00 36 00 34

text string of the hex = 1.9.9. .8.3.0. .5.6.4

sometime this numbers change with a random value for example 1 9 9 become 6 2 2

8 3 0 became 9 4 1

5 6 4 became 4 3 3

how i can do a search of this hex = 31 00 39 00 39 00 20 00 38 00 33 00 30 00 20 00 35 00 36 00 34

without know the numbers ?

macos – Finder ‘find’ function finds nothing, no matter which directory is searched

Simple as that. Whatever I search (even copy pasting an existing file’s name) finds 0 results. Doesnt matter if i search my mac or the current directory, it always comes up with 0 results. I tried restarting finder and my computer, but with no success. The same thing seems to also happen with find command in terminal (find . -name ). Is there any way to fix this?

postgresql – LARAVEL PostGre PDOException: could not find driver

Estou tentando realizar a conexão ao um banco de dados PostGre porem estou recebendo este erro
do laravel:

 PDOException: could not find driver in C:Autobots...

E esse

 IlluminateDatabaseQueryException: could not find driver (SQL: select * from 

Meu php.ini no XAMP esta com a seguinte configuração

;extension=exif      ; Must be after mbstring as it depends on it
;extension=oci8_12c  ; Use with Oracle Database 12c Instant Client

Alguém saberia o motivo de tal erro estar ocorrendo?

blockchain – How to find Z value of multisig transaction?

What you’re asking for is how to figure out what to sign for a multisig transaction.

Multisig is actually very close to this answer. There are a few subtle differences, however, so let me try to summarize step-by-step using the transaction as seen on the blockchain

Note that for each input, the actual hash to be signed is going to be different. Namely, you will need to fill in the redeem script for that input only and nulls for every other input. To illustrate, let’s figure out what you need to sign for the very first input.

  1. Transaction version: 01000000
  2. Number of inputs: 03
  3. Tx input #1 hash: fdb1fe0b4506f8d412f8498a0d747701bc5ed8c009e779ee670c82361c1d1dd5
  4. Tx input #1 index: 01000000
  5. Tx input #1 redeem script length: 47 (71 bytes)
  6. Tx input #1 redeem script: 522102cebf6ab580948d146b7cc771d8e646974349d3d7b11f3e03287d0997a477d3b921037ba651485b7a2cb222191eb64a55926e62bbabfe9b5ed2a9488aad547b20428252ae
  7. Tx input #1 sequence: ffffffff
  8. Tx input #2 hash: a614d26f1878078a00a3c296085576cd7e6361234ea82c865681041fcfdacea8
  9. Tx input #2 index: 01000000
  10. Tx input #2 redeem script length: 00 (nothing)
  11. Tx input #2 sequence: ffffffff
  12. Tx input #3 hash: d064d2f9cf9e5196a9d81dd87718c9cfbec97f3ccac7164946d956421597c7f1
  13. Tx input #3 index: 01000000
  14. Tx input #3 redeem script length: 00 (nothing)
  15. Tx input #3 sequence: ffffffff
  16. Number of outputs: 01000000
  17. Amount being sent to the first (and only) output: e068704600000000
  18. Output script length: 19
  19. Output script: 76a9142c76e6fdd1a81c902afa62e78ec71435708d9d9d88ac
  20. Lock time field: 00000000
  21. SIGHASH_ALL: 01000000

Now, if you double-sha256 these bytes you get:


And indeed when you check against the embedded signature of that transaction, you can see that that is indeed the hash that was signed. Here’s a code sample to verify using the excellent btcd library written in go:

package main

import (


// Calculate the hash of hasher over buf.
func calcHash(buf ()byte, hasher hash.Hash) ()byte {
    return hasher.Sum(nil)

// Hash160 calculates the hash ripemd160(sha256(b)).
func Hash256(buf ()byte) ()byte {
    return calcHash(calcHash(buf, fastsha256.New()), fastsha256.New())

func main() {
    x := "0100000003fdb1fe0b4506f8d412f8498a0d747701bc5ed8c009e779ee670c82361c1d1dd50100000047522102cebf6ab580948d146b7cc771d8e646974349d3d7b11f3e03287d0997a477d3b921037ba651485b7a2cb222191eb64a55926e62bbabfe9b5ed2a9488aad547b20428252aeffffffffa614d26f1878078a00a3c296085576cd7e6361234ea82c865681041fcfdacea80100000000ffffffffd064d2f9cf9e5196a9d81dd87718c9cfbec97f3ccac7164946d956421597c7f10100000000ffffffff01e0687046000000001976a9142c76e6fdd1a81c902afa62e78ec71435708d9d9d88ac0000000001000000"

    b, _ := hex.DecodeString(x)

    hash := Hash256(b)
    fmt.Printf("hash of thing to sign: %xn", hash)

    pubkeyStr := "02cebf6ab580948d146b7cc771d8e646974349d3d7b11f3e03287d0997a477d3b9"
    pubkeyStr2 := "037ba651485b7a2cb222191eb64a55926e62bbabfe9b5ed2a9488aad547b204282"
    pubkeyBytes, _ := hex.DecodeString(pubkeyStr)
    pubkeyBytes2, _ := hex.DecodeString(pubkeyStr2)

    p, _ := btcec.ParsePubKey(pubkeyBytes, btcec.S256())
    p2, _ := btcec.ParsePubKey(pubkeyBytes2, btcec.S256())

    fmt.Printf("pubkeys: %s, %sn", p, p2)

    sigStr := "3044022025332b6dabf11e493fbc62c93e7302c48666512e1cf88157c26176f4af6d064702201ee7ec25d0917244e514c402e8751f112dfd1bef2b22ec5e496fbafabb52bf010148"

    sigStr2 := "3045022100fa1f17bf59bee0ac33ae5f682711c5471c73a4aeb898aee218478289a4c7aa6e02207b40dfeae3fa4a50dc147bd42be40370d76a35d72c0b27b27c4ba2439a565fb901"

    sigBytes, _ := hex.DecodeString(sigStr)
    sigBytes2, _ := hex.DecodeString(sigStr2)

    s, _ := btcec.ParseDERSignature(sigBytes, btcec.S256())
    s2, _ := btcec.ParseDERSignature(sigBytes2, btcec.S256())

    fmt.Printf("sig: %sn", s)

    fmt.Printf("signature valid: %vn", s.Verify(hash, p))
    fmt.Printf("signature valid: %vn", s2.Verify(hash, p2))


You can do the same thing with input #2 and input #3 to get the hash that gets signed by changing #5 and #6 (combined) to be 00 and #10 or #14 in the steps above to be 47522102cebf6ab580948d146b7cc771d8e646974349d3d7b11f3e03287d0997a477d3b921037ba651485b7a2cb222191eb64a55926e62bbabfe9b5ed2a9488aad547b20428252ae

Can you find the BBC Intelligence Squared podcast?

Within the context of subscribing to podcasts with TuneIn where is the BBC version for intelligence squared podcasts? The US version certainly has an RSS feed.

I’d like to listen to BBC intelligence squared podcasts on TuneIn but can’t find the details.

See also:

Could this be used to find the largest path in a graph?

Savitch’s theorem “test[s] the existence of a path from a vertex s to another vertex t that uses at most k edges”

Could this be used to find the largest path in a graph?

We know there’s a walk of length a from b to c.
We can keep lowering a by 1 to find a d where there’s no walk from b to c. Now we know there’s a path of length d+1 between b and c. We can try other b and c to maximize d+1. Does this find the largest path in the graph?

What is my mistake?

wp admin – How do I find a form managed by the Elementor plugin

I have a form on a WordPress site I acquired. Inspecting the HTML, I can see the following markup for the form:

<form class="elementor-form" method="post" id="newsletter_sign_up_desktop" name="Newsletter Sign Up Desktop" style="opacity: 1;">
            <input type="hidden" name="post_id" value="16170">
            <input type="hidden" name="form_id" value="2505af47">

The problem is, this form has a transition/slide in effect. When I edit the home page with Elementor, I cannot for the life of me find it to edit it.

What’s the best way for me to locate where this form is in wp-admin so I can edit it?

How to find the threshold of hash inequality at a given time?

For a miner to mine in bitcoin, he should find a nonce s.t the hash of block <= threshold. At a given time lets assume the total hash rate of the network be A hashes/sec and the mining rate be f blocks/sec. Is there way any to calculate this threshold from these parameters?

linear algebra – How to find a basis for the vector space of polynomials st f(-1) = f(2) of deg equal or less then 2?

I have the following vector space and I want to find a basis for it and after that complete it to be a basis of the entire vector space os polynomials of degree 2 or less.

I got the following basis (1, x -x^2 ) by equating a-b+c = a+2b+4c an getting b=-c but the second polynomial doesn’t fulfill p(-1) = p(2) so I guess it is wrong.

Also how could I complete it to the basis of the full R2(x)vector space?

I would really appreciate any help.