All Questions

I am trying to prove with the pumping lemma if the expression described in the title is a regular language or not, this is what I have tried:

∑={a,b}

∃(w)∈L y w = a^i b^j a  , siendo i,j>=0

|w| = 2n+1 >=n , cumple la condicion de |w| >= n

We know that w = xyzwith which:

|xy| <= n   ^   1 <= |y| <= n

Being X=a^p, y=a^qand that p+q<=n I would stay in the endz=a^(n-p-q) b^n a

This way it would stay|w|= p+q+n-p-q+n+1

checking the property of: x y^j z ∈ Lfor all j >=0, we have to create a new chain with j=2: w' = x y^2 zwith which it would be:

p + 2q + n - p - q + n + 1 =  2n + 1

In the end it is simplified to: q+2n+1 = 2n+1 that is only true if q=0which cannot be since the property of the pumping lemma itself says1<=|y|<=n

What I don't understand is that if I apply this with a string, for example:

w = aaaba

With n=2we can divide winto:

x=a
y=a
z=aba

With which for any y^ithat occurs to us as long as it is >=0, it should be accepted, since it ends in ano ??

I need to know how I would obtain the last Monday of each month, since in the program that I have to do, that last Monday of each month I must generate interest, but I don't know how I could calculate it.

try to get the total days of the month and subtract 7 days but obviously the result will not always be a Monday.

  DateTime fechaHoy = (DateTime)fechahoy.Value.Date;
  DateTime fechabono = FechaAbono.Value.Date;


  int anyo = fechabono.Year;
  int mes = fechabono.Month;
  int dias = DateTime.DaysInMonth(anyo, mes);

  int anyoHoy = fechaHoy.Year;
  int mesHoy = fechaHoy.Month;
  int diasHoy = DateTime.DaysInMonth(anyoHoy, mesHoy);

  int totaldiashoy = DateTime.DaysInMonth(anyoHoy, mesHoy);// 31 dias
  int totaldias = totaldiashoy - 7;

I am trying to make a cron that runs every X time on the android system so that it calls a service that I have made.

The features of the cron that I want to do are the following:

1. run regardless of whether the Application is running or not (partially done with the OnBootReceiver )
2. to run when the device reboots (I have it done, see code below on OnBootReceiver )
3. run every X time interval (every 10 minutes for example)
4. if there is no connection at the time of executing the service when the cron has been activated, a Receiverconnection is activated so that when there is a connection the service is executed and then it is deactivated Receiver(I have done it see code below in ConnectivityReceiver ).

Some of these features I have already achieved by doing them separately, below I put the code of what I have.

ConnectivityReceiver

public class ConnectivityReceiver extends WakefulBroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {

        if (intent.getAction().equals(ConnectivityManager.CONNECTIVITY_ACTION)) {

            boolean noConnectivity =
                    intent.getBooleanExtra(ConnectivityManager.EXTRA_NO_CONNECTIVITY, false);

            if(!noConnectivity){
                ConnectivityManager cm = (ConnectivityManager) context
                        .getSystemService(Context.CONNECTIVITY_SERVICE);
                NetworkInfo netInfo = cm.getActiveNetworkInfo();

                // only when connected or while connecting...
                if (netInfo != null && netInfo.isConnectedOrConnecting()) {
                    // if we have mobile or wifi connectivity...
                    if ((netInfo.getType() == ConnectivityManager.TYPE_MOBILE)
                            || (netInfo.getType() == ConnectivityManager.TYPE_WIFI)) {

                        Intent i =  new Intent(context, EnvioEstadisticasService.class);

                        startWakefulService(context, i);

                        // disable receiver after we started the service
                        disableReceiver(context);
                    }
                }
            }
        }
    }

    /**
     * Enables ConnectivityReceiver
     *
     * @param context
     */
    public static void enableReceiver(Context context) {
        ComponentName component = new ComponentName(context, ConnectivityReceiver.class);

        context.getPackageManager().setComponentEnabledSetting(component,
                PackageManager.COMPONENT_ENABLED_STATE_ENABLED, PackageManager.DONT_KILL_APP);
    }

    /**
     * Disables ConnectivityReceiver
     *
     * @param context
     */
    public static void disableReceiver(Context context) {
        ComponentName component = new ComponentName(context, ConnectivityReceiver.class);

        context.getPackageManager().setComponentEnabledSetting(component,
                PackageManager.COMPONENT_ENABLED_STATE_DISABLED, PackageManager.DONT_KILL_APP);
    }
}

ShippingStatisticsService

public class EnvioEstadisticasService extends IntentService {

    private static EstadisticasDAO daoEst;

    public EnvioEstadisticasService() {
        super("EnvioEstadisticasService");
    }

    @Override
    protected void onHandleIntent(Intent intent) {

        //hago todas las operaciones en envio de estadisticas

        // Release the wake lock provided by the WakefulBroadcastReceiver.
        ConnectivityReceiver.completeWakefulIntent(intent);
    }
}

OnBootReceiver

public class OnBootReceiver extends BroadcastReceiver {
    private static final String TAG = OnBootReceiver.class.getSimpleName();

    @Override
    public void onReceive(Context context, Intent intent) {

        if (intent.getAction().equals("android.intent.action.BOOT_COMPLETED")) {
            Log.i(TAG, "EnvioEstadisService: entra en el on bootreceiver");

            Intent i =  new Intent(context, EnvioEstadisticasService.class);
            startWakefulService(context, i);
        }
    }
}

And finally in manifest

<!-- Cron -->
        <receiver android:name=".cron.OnBootReceiver">
            <intent-filter>
                <action android:name="android.intent.action.BOOT_COMPLETED" />
            </intent-filter>
        </receiver>
        <receiver
            android:name=".cron.ConnectivityReceiver"
            android:enabled="false" >
            <intent-filter>
                <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
            </intent-filter>
        </receiver>

        <service android:name=".services.EnvioEstadisticasService"
            android:exported="false"
            android:enabled="true">
        </service>
        <!--  -->

I have managed to activate the service when the device is turned on or restarted regardless of the execution of the application, in addition to controlling the connection issue when sending to be able to call another receiver.

Does anyone know how to make it run every X interval regardless of whether the application is running or not?

With jQuery and other JavaScript libraries you can easily make AJAX calls using something like this:

$.ajax({
   url: "miURl",
   method: "GET",
   data: "var1=valor1&var2=valor2",
   success: function(d) {
      // código aquí
   }
});

The problem is that in some projects I have found that I added JavaScript libraries exclusively to use the AJAX function and for quite basic calls (mainly GETs in which I did not care about the error, only the result, if any)... and not it makes a lot of sense to add an 85-300KB file just for that.

What would a basic JavaScript function look like that takes a URL as a parameter, a function that will do success(I don't care about the error) and optionally the method (GET or POST), a list of variables, and work "similar" to how does it do it jQuery.ajax?

The response must be independent of the server it is running on and if that is not possible then it must work for Apache.

At work we run into an interesting problem: we have a page with a dropdown list that, when the selected option changes, updates the values ​​of a series of items from the values ​​of a JSON variable.

The HTML is something like this (simplified):

<select id="paises">
  <option value="chile">Chile</option>
  <option value="colombia">Colombia</option>
  <option value="ecuador">Ecuador</option>
</select>

<div id="valores">
  Pais: <span id="pais"></span><br/>
  Teléfono: <span id="telefono"></span><br/>
  Email: <span id="email"></span>
</div>

And the JSON is something like this (simplified):

info = {
    "chile": {
        "nombre": "Chile",
        "telefono": "123456789",
        "email": "[email protected]"
    },
    "colombia": {
        "nombre": "Colombia",
        "telefono": "192837465",
        "email": "[email protected]"
    },
    "ecuador": {
        "nombre": "Ecuador",
        "telefono": "987654321",
        "email": "[email protected]"
    }
}

The JavaScript code is not relevant to the question, but the idea is simple: depending on the selected country, the span. For example, if Chile is selected, the one spanwith id "country" will contain "Chile", the one spanwith id "phone" will show "123456789", etc, etc.

Now that page has been moved to a new CMS and for different reasons we are limited in the components we can use and none of them allow us to embed JavaScript (not even inline ), they only let us embed HTML and CSS.

So the question would be: how can the behavior described above be simulated, but exclusively using HTML+CSS without any JavaScript or JSON?

Regarding HTML and CSS we have no limitations: we can reorder/arrange the elements as we want, we can add new elements/remove existing elements, we can add as much code as we want... as long as it doesn't contain any script, just HTML and CSS.

For example, we finally found a solution (I'll share it in the answers below for inspiration) by replacing the selectwith a list ul, transforming the JSON to CSS (with :beforeand content) and with a series of inputhidden s... but the problem is that it takes up too much space and we want to know if there would be a different method.