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Question 1575: A Fixed-Length Discrete Orbit Prefix

On this page
  1. Original question and givens
  2. Definition and scope
  3. Step-by-step derivation
  4. Reverse checks
  5. Result
  6. This question review and source binding

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R0002-01575 · q-20261013-advance-20261020-r01-discrete-dynamical-system-0050

Original question and givens

Use the complete finite self-map on Fin(9)={0,…,8} given by T(x)=(a*x+b) mod 9, a=25, b=65. Choose the least nonnegative residue, including for negative a*x+b. Time is discrete, indexed from 0; a finite orbit is not a general stability result. x0=6, updates=6. Give (modulus, a, b, x0, update count, orbit including x0). Zero updates gives the one-element prefix [x0].

  • G001 — Use the complete finite self-map on Fin(9)={0,…,8} given by T(x)=(a*x+b) mod 9, a=25, b=65. Choose the least nonnegative residue, including for negative a*x+b. Time is discrete, indexed from 0; a finite orbit is not a general stability result. x0=6, updates=6. Give (modulus, a, b, x0, update count, orbit including x0). Zero updates gives the one-element prefix [x0].

Definition and scope

Use the original question domain, assumptions and cited MKO definitions. This item has second-context mathematical and bilingual review, with the model, answer and every arithmetic step independently recomputed from the original parameters; the source question remains a candidate.

Step-by-step derivation

S001 · implies

Before

X={0 through 8}; T(x)=(25x+(65)) mod 9

After

remainder representative always lies in X

Conditions: none

Fix the full finite state carrier and the same update rule;negative integers also use the standard remainder from0 through n−1.

Step identifiers and dependencies

Rule: finite_total_map · Uses: G001

S002 · implies

Before

x₀=6; transitions=6

After

initial orbit prefix=[6]

Conditions: none

Retain the initial state;steps=0 still has one known state,not an empty list.

Step identifiers and dependencies

Rule: orbit_initial_state · Uses: G001, S001

S003 · calculation

Before

transition1: a·x := mul(25, 6)

After

transition1: a·x = 150

Conditions: none

Multiply the original coefficient by the current state;do not clip negative values to0.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · calculation

Before

transition1: a·x+b := sum(150, 65)

After

transition1: a·x+b = 215

Conditions: none

Add the same offset before reducing modulo n.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · implies

Before

reduce 215 modulo 9

After

215=23·9+8

Conditions: none

The integer identity together with0≤remainder<n determines the next state.

Step identifiers and dependencies

Rule: euclidean_remainder · Uses: G001, S004

S006 · calculation

Before

transition2: a·x := mul(25, 8)

After

transition2: a·x = 200

Conditions: none

Multiply the original coefficient by the current state;do not clip negative values to0.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S005

S007 · calculation

Before

transition2: a·x+b := sum(200, 65)

After

transition2: a·x+b = 265

Conditions: none

Add the same offset before reducing modulo n.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S006

S008 · implies

Before

reduce 265 modulo 9

After

265=29·9+4

Conditions: none

The integer identity together with0≤remainder<n determines the next state.

Step identifiers and dependencies

Rule: euclidean_remainder · Uses: G001, S007

S009 · calculation

Before

transition3: a·x := mul(25, 4)

After

transition3: a·x = 100

Conditions: none

Multiply the original coefficient by the current state;do not clip negative values to0.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S008

S010 · calculation

Before

transition3: a·x+b := sum(100, 65)

After

transition3: a·x+b = 165

Conditions: none

Add the same offset before reducing modulo n.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S009

S011 · implies

Before

reduce 165 modulo 9

After

165=18·9+3

Conditions: none

The integer identity together with0≤remainder<n determines the next state.

Step identifiers and dependencies

Rule: euclidean_remainder · Uses: G001, S010

S012 · calculation

Before

transition4: a·x := mul(25, 3)

After

transition4: a·x = 75

Conditions: none

Multiply the original coefficient by the current state;do not clip negative values to0.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S011

S013 · calculation

Before

transition4: a·x+b := sum(75, 65)

After

transition4: a·x+b = 140

Conditions: none

Add the same offset before reducing modulo n.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S012

S014 · implies

Before

reduce 140 modulo 9

After

140=15·9+5

Conditions: none

The integer identity together with0≤remainder<n determines the next state.

Step identifiers and dependencies

Rule: euclidean_remainder · Uses: G001, S013

S015 · calculation

Before

transition5: a·x := mul(25, 5)

After

transition5: a·x = 125

Conditions: none

Multiply the original coefficient by the current state;do not clip negative values to0.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S014

S016 · calculation

Before

transition5: a·x+b := sum(125, 65)

After

transition5: a·x+b = 190

Conditions: none

Add the same offset before reducing modulo n.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S015

S017 · implies

Before

reduce 190 modulo 9

After

190=21·9+1

Conditions: none

The integer identity together with0≤remainder<n determines the next state.

Step identifiers and dependencies

Rule: euclidean_remainder · Uses: G001, S016

S018 · calculation

Before

transition6: a·x := mul(25, 1)

After

transition6: a·x = 25

Conditions: none

Multiply the original coefficient by the current state;do not clip negative values to0.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S017

S019 · calculation

Before

transition6: a·x+b := sum(25, 65)

After

transition6: a·x+b = 90

Conditions: none

Add the same offset before reducing modulo n.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S018

S020 · implies

Before

reduce 90 modulo 9

After

90=10·9+0

Conditions: none

The integer identity together with0≤remainder<n determines the next state.

Step identifiers and dependencies

Rule: euclidean_remainder · Uses: G001, S019

S021 · implies

Before

computed transitions=6

After

orbit=[6, 8, 4, 3, 5, 1, 0]; number of entries=7

Conditions: none

Apply the same T to the preceding result; k transitions give k+1 states.

Step identifiers and dependencies

Rule: orbit_prefix_length · Uses: G001, S020

S022 · implies

Before

a finite requested prefix

After

no unrequested least-period claim

Conditions: none

This output is the requested prefix;it is not an unverified least-period proof from a few orbit values.

Step identifiers and dependencies

Rule: finite_prefix_scope · Uses: G001, S021

Reverse checks

  • S022 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S021 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S020 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S019 · premise_and_result_audit — Recompute transition6: a·x+b with exact rational arithmetic, not rounded decimals.
  • S018 · premise_and_result_audit — Recompute transition6: a·x with exact rational arithmetic, not rounded decimals.
  • S017 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S016 · premise_and_result_audit — Recompute transition5: a·x+b with exact rational arithmetic, not rounded decimals.
  • S015 · premise_and_result_audit — Recompute transition5: a·x with exact rational arithmetic, not rounded decimals.
  • S014 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S013 · premise_and_result_audit — Recompute transition4: a·x+b with exact rational arithmetic, not rounded decimals.
  • S012 · premise_and_result_audit — Recompute transition4: a·x with exact rational arithmetic, not rounded decimals.
  • S011 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S010 · premise_and_result_audit — Recompute transition3: a·x+b with exact rational arithmetic, not rounded decimals.
  • S009 · premise_and_result_audit — Recompute transition3: a·x with exact rational arithmetic, not rounded decimals.
  • S008 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S007 · premise_and_result_audit — Recompute transition2: a·x+b with exact rational arithmetic, not rounded decimals.
  • S006 · premise_and_result_audit — Recompute transition2: a·x with exact rational arithmetic, not rounded decimals.
  • S005 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S004 · premise_and_result_audit — Recompute transition1: a·x+b with exact rational arithmetic, not rounded decimals.
  • S003 · premise_and_result_audit — Recompute transition1: a·x with exact rational arithmetic, not rounded decimals.
  • S002 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S001 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.

Result

(9, 25, 65, 6, 6, [6, 8, 4, 3, 5, 1, 0])

The full substitutions and premise checks give the original answer; source identity,format and status are unchanged.

This question review and source binding

Review date: 2026-10-26

Original questions, answers, step expressions, numeric ASTs and historical records are retained. Source candidate labels remain historical and are not overwritten as formal proof.

Source hashes and review receipts
  • input commit: 0f7be61e2c22317a4075561dc822c87d881a50db
  • original question SHA-256: 23cc4118f038fdc8d53e66f058bc841586354c0f63ce7521dbb4d2e7e07a0cce
  • candidate record SHA-256: 66aff0e7cf08c7c774797e191425cef78c537583111e12226a92796d092300d6
  • semantic review receipt SHA-256: 340d74dcc6e37df6249594a0b79a9ee2af804337b7847478b3c1342af9722861
  • question-first witness SHA-256: 9a06233d190d31a16f13fb03b6c3ceba4cbb748fff6c997941f66ab1888dcca8
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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