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Question 16982: A Spanning Family May Give a Loose Upper Bound

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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R0032-16982 · q-20261014-advance-20261102-r01-vector-space-dimension-0082

Original question and givens

Use the complete ordered real coordinate family vectors=[[1, 0], [0, 1], [7, 1]] in ambient R^2, limited to dimensions 2 or 3. Treat vectors as columns and calculate rank by exact rational Gaussian elimination, not floating-point samples. A basis is both independent and spanning. An independent family gives only a lower bound; a spanning family gives only an upper bound. Basis-cardinality invariance uses the finite-dimensional theorem, not a few examples. Give (vector_count,rank,spanning?,upper_bound). The last field is dimension_at_most_vector_count with the numeric count, or no_upper_bound_from_nonspanning_family.

  • G001 — Use the complete ordered real coordinate family vectors=[[1, 0], [0, 1], [7, 1]] in ambient R^2, limited to dimensions 2 or 3. Treat vectors as columns and calculate rank by exact rational Gaussian elimination, not floating-point samples. A basis is both independent and spanning. An independent family gives only a lower bound; a spanning family gives only an upper bound. Basis-cardinality invariance uses the finite-dimensional theorem, not a few examples. Give (vector_count,rank,spanning?,upper_bound). The last field is dimension_at_most_vector_count with the numeric count, or no_upper_bound_from_nonspanning_family.

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

same usual real ambient R^2;original ORDERED vectors as columns=[[1, 0], [0, 1], [7, 1]]

After

complete row-coordinate matrix=[[1, 0, 7], [0, 1, 1]];vector count=3;zero/repeated vectors retained

Conditions: none

Columns are the original vectors and rows their coordinates.Zero and repeated vectors are allowed,so semantic-template deduplication cannot replace the original family or its count.Exact rational row operations are invertible coordinate changes over the reals.

Step identifiers and dependencies

Rule: dimension_actual_columns_not_semantic_deduplication · Uses: G001

S002 · calculation

Before

dimension pivot row0 column0 normalized entry0 := div(1, 1)

After

dimension pivot row0 column0 normalized entry0 = 1

Conditions: none

Compute exactly from original roles and established intermediates,retaining indices,denominators,signs and operation roles.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S001

S003 · calculation

Before

dimension pivot row0 column0 normalized entry1 := div(0, 1)

After

dimension pivot row0 column0 normalized entry1 = 0

Conditions: none

Compute exactly from original roles and established intermediates,retaining indices,denominators,signs and operation roles.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S002

S004 · calculation

Before

dimension pivot row0 column0 normalized entry2 := div(7, 1)

After

dimension pivot row0 column0 normalized entry2 = 7

Conditions: none

Compute exactly from original roles and established intermediates,retaining indices,denominators,signs and operation roles.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S003

S005 · implies

Before

pivot row=0;pivot column=0;nonzero exact pivot=1;old row=[1, 0, 7]

After

divide whole row by pivot;normalized row=[1, 0, 7]

Conditions: none

Divide the whole row by the same nonzero pivot,showing every exact fraction.Do not change only the pivot cell or use floating-point approximations.Multiplying back by the pivot reverses the step.

Step identifiers and dependencies

Rule: dimension_nonzero_pivot_scaling_every_entry · Uses: G001, S004

S006 · calculation

Before

dimension pivot row1 column1 normalized entry0 := div(0, 1)

After

dimension pivot row1 column1 normalized entry0 = 0

Conditions: none

Compute exactly from original roles and established intermediates,retaining indices,denominators,signs and operation roles.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S005

S007 · calculation

Before

dimension pivot row1 column1 normalized entry1 := div(1, 1)

After

dimension pivot row1 column1 normalized entry1 = 1

Conditions: none

Compute exactly from original roles and established intermediates,retaining indices,denominators,signs and operation roles.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S006

S008 · calculation

Before

dimension pivot row1 column1 normalized entry2 := div(1, 1)

After

dimension pivot row1 column1 normalized entry2 = 1

Conditions: none

Compute exactly from original roles and established intermediates,retaining indices,denominators,signs and operation roles.

Step identifiers and dependencies

Rule: exact_rational_arithmetic · Uses: G001, S007

S009 · implies

Before

pivot row=1;pivot column=1;nonzero exact pivot=1;old row=[0, 1, 1]

After

divide whole row by pivot;normalized row=[0, 1, 1]

Conditions: none

Divide the whole row by the same nonzero pivot,showing every exact fraction.Do not change only the pivot cell or use floating-point approximations.Multiplying back by the pivot reverses the step.

Step identifiers and dependencies

Rule: dimension_nonzero_pivot_scaling_every_entry · Uses: G001, S008

S010 · implies

Before

original column family count=3;ambient dimension=2;final exact matrix=[[1, 0, 7], [0, 1, 1]];pivot columns=[0, 1]

After

rank=2;independent=No;spans whole ambient=Yes;basis=No

Conditions: none

Invertible row operations preserve all real solutions of M*c=0.The pivot count is real rank,and independence requires rank equal to column count.Left multiplication by invertible E maps the original column span to its E-image,preserving dimension and whole-ambient spanning status,not literal equality of the two spans.Spanning requires rank=n;both conditions are needed for a basis.

Step identifiers and dependencies

Rule: dimension_pivots_relations_and_whole_ambient_spanning · Uses: G001, S009

S011 · implies

Before

supplied original vector count=3;exact rank=2;whole-ambient spanning=Yes

After

this family's upper-bound certificate=dimension_at_most_3

Conditions: none

A finite spanning family can be pruned to a basis,so dimension≤m;the bound can be loose.If it does not span,this family supplies no such certificate,not proof of infinite ambient dimension.Do not silently replace the original m by a tighter answer.

Step identifiers and dependencies

Rule: dimension_spanning_family_only_its_possibly_loose_upper_bound · Uses: G001, S010

Reverse checks

  • 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 — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S009 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S008 · premise_and_result_audit — Recompute dimension pivot row1 column1 normalized entry2 with exact rational arithmetic, not rounded decimals.
  • S007 · premise_and_result_audit — Recompute dimension pivot row1 column1 normalized entry1 with exact rational arithmetic, not rounded decimals.
  • S006 · premise_and_result_audit — Recompute dimension pivot row1 column1 normalized entry0 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 dimension pivot row0 column0 normalized entry2 with exact rational arithmetic, not rounded decimals.
  • S003 · premise_and_result_audit — Recompute dimension pivot row0 column0 normalized entry1 with exact rational arithmetic, not rounded decimals.
  • S002 · premise_and_result_audit — Recompute dimension pivot row0 column0 normalized entry0 with exact rational arithmetic, not rounded decimals.
  • S001 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.

Result

(3, 2, Yes, dimension_at_most_3)

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: 3a92d60f09067a815e1391cc15b25fbc12c59e1c76a9104e11a05495968b2eeb
  • candidate record SHA-256: eb8332998f686d9dc5ff22dfddfb17283149f229973297c8ed88f8472a993ce2
  • semantic review receipt SHA-256: d64b4e08bda1c25dd393b7c7e4140a8734610a9b84ae47e6f0adcff7f30a0b8e
  • question-first witness SHA-256: 790fd6623c04ba52a6ffb0a95cea52b532a02b23bb9453926d2d9f7a825fdec8
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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