## If i have a Language that accepts all words in a given alphabet will there always be a subset of that language that is undecidable?

I know that the language $$L$$ = { $$a^n|nin N$$} is infinite- yet decidable.
But are there always subsets of that (or any other infinite language) that are undecidable?

## network – Beware: macOS Finder “Connect to Server” accepts FTPS URLs (FTP in a SSL/TLS tunnel) but actually connects via plain FTP!

network – Beware: macOS Finder “Connect to Server” accepts FTPS URLs (FTP in a SSL/TLS tunnel) but actually connects via plain FTP! – Ask Different

## How can I implement a Deterministic finite automaton which accepts

Problem: implement a Deterministic finite automaton which accepts 01 ∪ (2∪10*2)*

∪ <- is union symbol

I have a lot of problem trying to implement that DFA, the union symbol always confuse me
Can someone help me

## finite automata – Construct a DFA accepts set of all strings that begins with 01 and end with 11

By clicking “Accept all cookies”, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy.

## time – Duration field that accepts a number of weeks and days

### Try helper text below, so there’s no memory tax once they start entering a format.

Another option you can also look at is using a forgiving format pattern

This means if a user enters ‘2 weeks, 1 day’ that is still recognized by the application. It’s conforming the application to a human, rather than forcing the human to think in terms of data input for a machine.

From designing interfaces:

The user just wants to get something done, not think about “correct” formats and complex UIs. Computers are good at figuring out how to handle input of different types (up to a point, anyway). It’s a perfect match: let the user type whatever he needs, and if it’s reasonable, make the software do the right thing with it.

This might take more investment, and is not worth it at the moment, but it’s an aspirational goal for UX at any time.

## ❕NEWS – Miami Pharmacy Accepts Bitcoin From Conference Attendees for COVID Tests | Proxies-free

Earlier before the recent or just concluded Bitcoin conference held in Miami , the progressive health care pharmacy in Miami announced it willingness to accept payment for covid test in Bitcoin from the participants considering that the participants could be up to 50,000 people.

What do you think of this move?.

## pushdown automata – How to show that pda accepts empty language?

I have to show that a PDA accepts empty language, but for this I have to use some algorithm, with what kind of algorithms could I demonstrate it? I’ve heard about the algorithm from Moore, Brzozowski or Thompson, but they are for DFA, so I don’t know if it would work.

## formal languages – Designing CFG that accepts \$a^n b^m c^p\$ where \$n=m+p+2\$

I have generated the CFG of $$a^n b^m c^p$$ where $$m = n+p+2$$:

$$S rightarrow ASC mid varepsilon$$

$$A rightarrow aAb mid varepsilon$$

$$C rightarrow bCc mid varepsilon$$

I have been trying $$a^n b^m c^p$$ where $$n=m+p+2$$ but cannot figure out how to represent $$n=m+p+2$$.
Any hint would really be appreciated.

## formal languages – Whether there exists a Deterministic Infinite Automata (DIA), which accepts all strings in L and rejects all stings not in L?

Given an automata DIA I = (Q,Σ,δ,q0,F), and the set of states Q is infinite. The set of characters Σ is still finite.

Wondering whether there is an I and an arbitrary language L over Σ, such that I accepts all strings in L and rejects all strings not in L?