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Question 11978: Separate a Quadratic Objective Certificate from Feasible-Interval Qualification

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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R0022-11978 · q-20261013-advance-20261025-r03-convex-optimization-problem-0003

Original question and givens

Use the one-variable quadratic f(t)=a*t²+b*t+c with coefficients [a,b,c]=[2, -10, -1], not ascending-power order. The declared interval [lower,upper]=[-4, 5] belongs to the function data. Give (coefficients,interval,global quadratic certificate a≥0?,qualified nonempty ordered feasible interval?,both qualifications?,qualification_only_no_solution_claim). The objective flag uses the named global quadratic criterion; failure does not decide every possible restricted singleton case. Keep convex-objective qualification, convex feasible-domain qualification, point feasibility, evaluation and comparison separate. These checks supply no general solver, global optimum, existence, uniqueness, KKT or convergence claim.

  • G001 — Use the one-variable quadratic f(t)=a*t²+b*t+c with coefficients [a,b,c]=[2, -10, -1], not ascending-power order. The declared interval [lower,upper]=[-4, 5] belongs to the function data. Give (coefficients,interval,global quadratic certificate a≥0?,qualified nonempty ordered feasible interval?,both qualifications?,qualification_only_no_solution_claim). The objective flag uses the named global quadratic criterion; failure does not decide every possible restricted singleton case. Keep convex-objective qualification, convex feasible-domain qualification, point feasibility, evaluation and comparison separate. These checks supply no general solver, global optimum, existence, uniqueness, KKT or convergence claim.

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

declared interval record=[-4, 5]

After

ordered_nonempty=Yes;nondegenerate=Yes

Conditions: none

This nonempty-interval protocol uses lower≤upper;the nondegenerate certificate additionally needs lower<upper.A reversed record is unqualified,not a declaration that the abstract empty set is nonconvex.A singleton interval is convex.

Step identifiers and dependencies

Rule: interval_certificate_qualification_not_empty_set_nonconvexity · Uses: G001

S002 · implies

Before

univariate quadratic coefficients=[2, -10, -1];order=[a,b,c]

After

f(t)=(2)*t^2+(-10)*t+(-1)

Conditions: none

These are quadratic,linear,constant coefficients in descending order,not the constant-first boundary-polynomial order.Retain zero leading coefficients.

Step identifiers and dependencies

Rule: quadratic_descending_coefficient_order · Uses: G001, S001

S003 · implies

Before

f(t)=(2)*t^2+(-10)*t+(-1);z=lambda*x+(1-lambda)*y

After

rhs-lhs=(2)*(lambda*x^2+(1-lambda)*y^2-(lambda*x+(1-lambda)*y)^2)

Conditions: none

Expand both Jensen sides.The unit weight sum cancels the linear and constant terms exactly,leaving only the quadratic part.

Step identifiers and dependencies

Rule: jensen_linear_and_constant_terms_cancel · Uses: G001, S002

S004 · implies

Before

lambda*x^2+(1-lambda)*y^2-(lambda*x+(1-lambda)*y)^2

After

lambda*(1-lambda)*(x-y)^2;full gap=(2)*lambda*(1-lambda)*(x-y)^2

Conditions: none

Expand the square and collect x²,xy,y².The coefficients are lambda(1−lambda),−2lambda(1−lambda),lambda(1−lambda),yielding the(x−y)^2 factor for all real endpoints.

Step identifiers and dependencies

Rule: jensen_gap_full_symbolic_factorization · Uses: G001, S003

S005 · implies

Before

arbitrary x,y in [-4,5];0<=lambda<=1;z=lambda*x+(1-lambda)*y

After

z--4=lambda*(x--4)+(1-lambda)*(y--4)>=0;5-z=lambda*(5-x)+(1-lambda)*(5-y)>=0

Conditions: none

Both slacks are nonnegative sums,hence lower≤z≤upper for every endpoint pair and every permitted lambda.No sampling is used;endpoints and singleton cases are included.

Step identifiers and dependencies

Rule: interval_all_segments_slack_identity · Uses: G001, S004

S006 · implies

Before

global quadratic leading coefficient=2;interval record=[-4, 5]

After

global objective certificate=Yes;feasible interval certificate=Yes;qualified=Yes

Conditions: none

The objective flag is the global quadratic a≥0 criterion:for a<0,endpoints0,1 and half weights give a negative gap.The domain flag separately qualifies a nonempty ordered interval.Joint qualification proves no solution,uniqueness,KKT or solver convergence;failure of the global criterion does not classify every restricted singleton problem.

Step identifiers and dependencies

Rule: optimization_two_qualifications_not_solver · Uses: G001, S005

Reverse checks

  • S006 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • 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 — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • S003 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
  • 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

([2, -10, -1], [-4, 5], Yes, Yes, Yes, qualification_only_no_solution_claim)

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: 625ef78c3da23538df485165a1e9ff687b54bd289db8f38c266ace65178b08a1
  • candidate record SHA-256: 7b735406464136a63d22e30e32842b476b9504f28df12c30444fefdb1d97153b
  • semantic review receipt SHA-256: 94ec4350cf8b5e5c6c7701d536126eef20acb3a213e873ace4f5346d256b8fac
  • question-first witness SHA-256: 0beba165ffd367a7c96de3aa58344d572d01434cd2ef772fbb00342c1f50b01b
  • Lean: NOT_RUN · human review: NOT_PERFORMED
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