Does anybody recognise this? M.P=C, P=M^(-1).C, A/0 ... Z/25, mod 26

[PaulW]

I'm trying to solve a cryptic maths-based puzzle for which the starting information [in this exact format] is as follows:

M.P=C
P=M^(-1).C

A/0 ... Z/25
mod 26

I'm not even completely sure what format any answer should be in; the lower two lines [A/0 ... Z/25 mod 26] are, I believe, straightforward and indicate that whatever numerical string or matrix results from the first two lines can be used to generate a character string or matrix that would be the final answer [which would form part of the key for solving an enciphered message].

It is quite possible, maybe even likely, that the numerical string or matrix can be used to form a 5x5 square matrix.

My problem is that I have no idea what the 'equations' relate to, or even if the [presumed variables] M, P and C are significant or any other symbols [e.g. x,y,z] could have been used without affecting the meaning.

Does anybody have any idea?

 

[Otis]

From where does this puzzle come?

 

[PaulW]

It's the last element in a multi-stage geocache puzzle; the setter is known for his meticulous and mathematically literate approach so the answer is unlikely to be a trick or crude misdirection.

The fact that the two expressions are equivalent is interesting and vaguely suggests to me (although I am grasping at straws here!) something along the lines of a logic, set theory or matrix algebra problem ...

 

[Harry_the_cat]

I'm trying to solve a cryptic maths-based puzzle for which the starting information [in this exact format] is as follows:

You give us the "starting information". Can you post the puzzle in it's entirety please?

 

[PaulW]

I don't know if my last message will be posted - there's quite a gap between submitting and the message actually being posted (my messages need 'approval').

The entire puzzle (or this section of it, at any rate) is more to do with cipher decryption than anything else.

Effectively, there is a 72 letter alphabetic string to be decoded, a hidden 25 letter 5 x 5 character grid (all alphabet except M) and the posted 'clue'. I don't know for sure how the 'clue' is meant to be used to aid decryption!

 

[Harry_the_cat]

It's the last element in a multi-stage geocache puzzle; the setter is known for his meticulous and mathematically literate approach so the answer is unlikely to be a trick or crude misdirection.

The fact that the two expressions are equivalent is interesting and vaguely suggests to me (although I am grasping at straws here!) something along the lines of a logic, set theory or matrix algebra problem ...

Since it is a geocache problem, will the answer be a pair of co-ordinates?

Also can you please post the link to the original geocache problem?