let r be Real; :: thesis: for A being non empty closed_interval Subset of REAL

for f being Function of A,REAL

for D being Division of A st f | A is bounded & r >= 0 holds

(lower_sum_set (r (#) f)) . D <= (r * (upper_bound (rng f))) * (vol A)

let A be non empty closed_interval Subset of REAL; :: thesis: for f being Function of A,REAL

for D being Division of A st f | A is bounded & r >= 0 holds

(lower_sum_set (r (#) f)) . D <= (r * (upper_bound (rng f))) * (vol A)

let f be Function of A,REAL; :: thesis: for D being Division of A st f | A is bounded & r >= 0 holds

(lower_sum_set (r (#) f)) . D <= (r * (upper_bound (rng f))) * (vol A)

let D be Division of A; :: thesis: ( f | A is bounded & r >= 0 implies (lower_sum_set (r (#) f)) . D <= (r * (upper_bound (rng f))) * (vol A) )

assume that

A1: f | A is bounded and

A2: r >= 0 ; :: thesis: (lower_sum_set (r (#) f)) . D <= (r * (upper_bound (rng f))) * (vol A)

A3: rng f is bounded_above by A1, INTEGRA1:13;

A4: (r (#) f) | A is bounded by A1, RFUNCT_1:80;

then A5: upper_sum ((r (#) f),D) <= (upper_bound (rng (r (#) f))) * (vol A) by INTEGRA1:27;

(lower_sum_set (r (#) f)) . D = lower_sum ((r (#) f),D) by INTEGRA1:def 11;

then A6: (lower_sum_set (r (#) f)) . D <= upper_sum ((r (#) f),D) by A4, INTEGRA1:28;

upper_bound (rng (r (#) f)) = upper_bound (r ** (rng f)) by Th17

.= r * (upper_bound (rng f)) by A2, A3, Th13 ;

hence (lower_sum_set (r (#) f)) . D <= (r * (upper_bound (rng f))) * (vol A) by A6, A5, XXREAL_0:2; :: thesis: verum

for f being Function of A,REAL

for D being Division of A st f | A is bounded & r >= 0 holds

(lower_sum_set (r (#) f)) . D <= (r * (upper_bound (rng f))) * (vol A)

let A be non empty closed_interval Subset of REAL; :: thesis: for f being Function of A,REAL

for D being Division of A st f | A is bounded & r >= 0 holds

(lower_sum_set (r (#) f)) . D <= (r * (upper_bound (rng f))) * (vol A)

let f be Function of A,REAL; :: thesis: for D being Division of A st f | A is bounded & r >= 0 holds

(lower_sum_set (r (#) f)) . D <= (r * (upper_bound (rng f))) * (vol A)

let D be Division of A; :: thesis: ( f | A is bounded & r >= 0 implies (lower_sum_set (r (#) f)) . D <= (r * (upper_bound (rng f))) * (vol A) )

assume that

A1: f | A is bounded and

A2: r >= 0 ; :: thesis: (lower_sum_set (r (#) f)) . D <= (r * (upper_bound (rng f))) * (vol A)

A3: rng f is bounded_above by A1, INTEGRA1:13;

A4: (r (#) f) | A is bounded by A1, RFUNCT_1:80;

then A5: upper_sum ((r (#) f),D) <= (upper_bound (rng (r (#) f))) * (vol A) by INTEGRA1:27;

(lower_sum_set (r (#) f)) . D = lower_sum ((r (#) f),D) by INTEGRA1:def 11;

then A6: (lower_sum_set (r (#) f)) . D <= upper_sum ((r (#) f),D) by A4, INTEGRA1:28;

upper_bound (rng (r (#) f)) = upper_bound (r ** (rng f)) by Th17

.= r * (upper_bound (rng f)) by A2, A3, Th13 ;

hence (lower_sum_set (r (#) f)) . D <= (r * (upper_bound (rng f))) * (vol A) by A6, A5, XXREAL_0:2; :: thesis: verum