Choose x or y from each factor; commutativity permits grouping products by the number of y choices.
Step identifiers and dependencies
Rule: finite_product · Uses: G001
S002 · implies
Before
a product with zero factors in the polynomial ring
After
empty product = multiplicative identity = 1
Conditions: none
A finite product of zero factors is defined as the multiplicative identity, so the entire polynomial is the constant 1.
Step identifiers and dependencies
Rule: empty_product_convention · Uses: G001, S001
S003 · implies
Before
choose exactly 0 of 0 factors to contribute y
After
C(0,0)=1/(1·1)=1
Conditions: none
Count orderings of 0 positions and divide by reorderings within the 0 y positions and 0 x positions, giving coefficient 1.
Step identifiers and dependencies
Rule: subset_count · Uses: G001, S002
S004 · implies
Before
C(0,0)=1; choose y 0 times
After
1·x^0·y^0
Conditions: none
The x exponent is 0-0=0; the two exponents still sum to 0.
Step identifiers and dependencies
Rule: group_like_terms · Uses: G001, S003
S005 · implies
Before
all k=0 through 0 have been accounted for
After
(x+y)^0=1·x^0·y^0
Conditions: none
For n=0 the empty product is 1. The table's x^0 y^0 denotes the constant monomial, not an arithmetic evaluation of 0^0 at x=y=0.
Step identifiers and dependencies
Rule: collect_all_terms · Uses: G001, S004
Reverse checks
S005 · premise_and_result_audit — There are n+1 coefficient positions, with the complete range of k retained.
S004 · premise_and_result_audit — The answer row is [k,coefficient,x exponent,y exponent]; do not swap the exponent columns.
S003 · premise_and_result_audit — Check the coefficient independently with the integer Pascal recurrence, not approximate factorials.
S002 · premise_and_result_audit — This polynomial empty-product convention does not assign a separate arithmetic value to the number 0^0.
S001 · premise_and_result_audit — This is not an infinite expansion for a noninteger power or a claim for noncommuting multiplication.
Result
(0, [[0, 1, 0, 0]], constant_one_boundary)
The full expansion consists of all displayed monomials, in the same order as the answer rows.
This question review and source binding
Review date: 2026-10-24
Original questions, answers, step expressions, numeric ASTs and historical records are retained. Source candidate labels remain historical and are not overwritten as formal proof.