# Basics of merphology

## Murphy's Law

The universal philosophical principle is that if something bad can happen, it happens.

## Murphy's philosophy

Smile ... tomorrow will get worse.

## Murphy's constant

The degree of discrimination of any case is inversely proportional to its significance.

## Origin

In 1949, the causes of aircraft accidents were investigated at Edwards Air Force Base in California. Serving at the base, Captain Ed Murphy (var. Murphy; English Murphy), evaluating the work of technicians in one of the laboratories, argued that if you can do something wrong, then these technicians will do just that.

Northrop project manager J. Nichols called these persistent problems "Murphy's Law." At one of the press conferences, the Air Force colonel who was conducting it said that everything achieved in ensuring flight safety is the result of overcoming the "Murphy's Law". So the expression got into the press. In the next few months, this principle became widely used in industrial advertising and came to life.

## Wording

In modern terms, Murphy's law is usually most easily formulated in terms of classical probability theory:

If n tests are carried out, the result of each of which is estimated by a Boolean function z, and the result "false" is undesirable, then for a sufficiently large n, we will definitely obtain an undesirable result for at least one test A.

Murphy's Law is confirmed in all practical tests. To some extent, this makes Murphy's law similar to Fermat's Last Theorem.

## Callaghan's commentary

Murphy was optimistic.

Callaghan's comment was later reformulated in a more rigorous form as:

For any n, there is m, with m

## Consequences

The consequences of Murphy's Law were first published in the book "Murphy's Law" by Arthur Bloch. No attribution (most likely not Ed Murphy's own).

The investigations were published in verbal form, not devoid of humor. Today this form is called "canonical". All consequences in canonical formulations should be understood as taking place under the conditions of Murphy's law, i.e. for a sufficiently large number of trials, provided there is a function that evaluates the desirability or undesirability of a particular event. With this in mind, modern rigorous formulations of consequences have been developed.

The first-fifth consequences are formulated, like Murphy's law, in terms of probability theory; the sixth and seventh consequences are of a more general philosophical nature.

## First and second

Canonical formulation:

1) Everything is not as easy as it seems.

2) All work takes more time than you think.

This is essentially one principle. Its strict formulation:

If there is an evaluation function, and the desired values ​​are non-negative, and it is known that for n tests the function gives sufficiently reliable non-negative values, then there will always be m> n such that for m tests the function will necessarily give a significant number of negative values.

## Third

Canonical formulation:

Of all the troubles, the one with the greatest damage will occur.

Strict wording:

If there are several possible outcomes for each of the events, and some of the options are undesirable, and to varying degrees, then with an increase in the number of trials, the probability of the most undesirable option falling out tends to unity.

This consequence is rather controversial. Many scientists believe that even if Murphy's law is proven, the third consequence will not be proven; many scientists believe that it will be possible to refute it (to this day, however, this has not been done).

## Fourth

Canonical formulation:

If the four causes of possible troubles are eliminated in advance, then there is always a fifth.

Strict wording:

If the outcome of an event depends on an infinite number of a priori factors, and n of them are found that are reliably known to lead to an undesirable outcome, then there is always an (n + 1) -th such factor.

## Fifth

Canonical formulation:

Left to their own devices, events tend to go from bad to worse.

Strict wording:

With an unlimited increase in the number of trials, the likelihood of an undesirable outcome increases.

## Sixth

Canonical formulation:

As soon as you begin to do some work, there is another that needs to be done even earlier.

Strict wording:

For any process there is one, without the completion of which the given is impossible.

## Seventh

Canonical formulation:

Every solution breeds new problems.

Strict wording:

Eliminating factors that can lead to undesirable outcomes reveals new such factors.